1
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Clapham ML, Das A, Douglas CJ, Frontiera RR. Killer Phonon Caught: Femtosecond Stimulated Raman Spectroscopy Identifies Phonon-Induced Control of Photophysics in Rubrene Derivatives. J Am Chem Soc 2024. [PMID: 38991144 DOI: 10.1021/jacs.4c03249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Molecular reaction coordinates are defined by the interplay of a number of orthogonal nuclear coordinates and are inherently multidimensional for large molecules. Identifying how specific nuclear motions along these reaction coordinates can be used to drive and control chemical processes is a promising approach for the optimization of chemical outcomes and targeted synthetic design. Here, we used femtosecond stimulated Raman spectroscopy (FSRS) to quantify the effects of individual phonon nuclear motions on singlet fission in rubrene derivatives. Rubrene readily undergoes singlet fission and is amendable to chemical derivatization, yet the factors that impact the singlet fission yield are not fully understood. Crystal packing is known to play a significant role in both fission and carrier transport, and thus, we focused on the impact of phonon nuclear motions on the photophysics. We used four halogen-substituted rubrene crystals and successfully identified one specific phonon mode that suppresses singlet fission in these crystals. We used FSRS with single-pulse excitation and double-pulse excitation to coherently amplify each phonon mode and quantify its effects on the excited-state process. We found that coherent amplification of the specific phonon vibration involving twisting of the peripheral phenyl rings and tetracene core motions resulted in less ground-state depletion and fewer triplet state absorption. Our study demonstrated that it is possible to use coherent phonon excitation to influence the photophysical outcome, while also showing that FSRS with double-pulse excitation can be a successful tool for quantifying mode-selective contributions to photophysics.
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Affiliation(s)
- Margaret L Clapham
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455, United States
| | - Aritra Das
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455, United States
| | - Christopher J Douglas
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455, United States
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2
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Kuttruff J, Nabben D, Zimmermann AC, Ryabov A, Baum P. Terahertz control and timing correlations in a transmission electron microscope. SCIENCE ADVANCES 2024; 10:eadl6543. [PMID: 38924397 PMCID: PMC11204200 DOI: 10.1126/sciadv.adl6543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 05/17/2024] [Indexed: 06/28/2024]
Abstract
Ultrafast electron microscopy provides a movie-like access to structural dynamics of materials in space and time, but fundamental atomic motions or electron dynamics are, so far, too quick to be resolved. Here, we report the all-optical control, compression, and characterization of electron pulses in a transmission electron microscope by the single optical cycles of laser-generated terahertz light. This concept provides isolated electron pulses and merges the spatial resolution of a transmission electron microscope with the temporal resolution that is offered by a single cycle of laser light. We also report the all-optical control of multi-electron states and find a substantial two-electron and three-electron anticorrelation in the time domain. These results open up the possibility to visualize atomic and electronic motions together with their quantum correlations on fundamental dimensions in space and time.
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Affiliation(s)
| | | | | | - Andrey Ryabov
- Universität Konstanz, Fachbereich Physik, 78464 Konstanz, Germany
| | - Peter Baum
- Universität Konstanz, Fachbereich Physik, 78464 Konstanz, Germany
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3
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Weber J, Schäfer S. Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses. NANO LETTERS 2024; 24:5746-5753. [PMID: 38701367 PMCID: PMC11100287 DOI: 10.1021/acs.nanolett.4c00773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 05/05/2024]
Abstract
Surface charging is ubiquitously observable during in situ transmission electron microscopy of nonconducting specimens as a result of electron beam/sample interactions or optical stimuli and often limits the achievable image stability and spatial or spectral resolution. Here, we report on the electron-optical imaging of surface charging on a nanostructured surface following femtosecond multiphoton photoemission. By quantitatively extracting the light-induced electrostatic potential and studying the charging dynamics on relevant time scales, we gain insights into the details of the multiphoton photoemission process in the presence of an electrostatic background field. We study the interaction of the charge distribution with the high-energy electron beam and secondary electrons and propose a simple model to describe the interplay of electron- and light-induced processes. In addition, we demonstrate how to mitigate sample charging by simultaneously optically illuminating the sample.
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Affiliation(s)
- Jonathan
T. Weber
- Institute
of Physics, Carl-von-Ossietzky University
of Oldenburg, 26129 Oldenburg, Germany
- Department
of Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Sascha Schäfer
- Institute
of Physics, Carl-von-Ossietzky University
of Oldenburg, 26129 Oldenburg, Germany
- Department
of Physics, University of Regensburg, 93053 Regensburg, Germany
- Regensburg
Center for Ultrafast Nanoscopy (RUN), University
of Regensburg, 93053 Regensburg, Germany
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4
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Zhou F, Liu H, Zajac M, Hwangbo K, Jiang Q, Chu JH, Xu X, Arslan I, Gage TE, Wen H. Ultrafast Nanoimaging of Spin-Mediated Shear Waves in an Acoustic Cavity. NANO LETTERS 2023; 23:10213-10220. [PMID: 37910440 DOI: 10.1021/acs.nanolett.3c02747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Strong spin-lattice coupling in van der Waals (vdW) magnets shows potential for innovative magneto-mechanical applications. Here, nanoscale and picosecond imaging by ultrafast electron microscopy reveal heterogeneous spin-mediated coherent acoustic phonon dynamics in a thin-film cavity of the vdW antiferromagnet FePS3. The harmonics of the interlayer shear acoustic modes are observed, in which the even and odd harmonics exhibit distinct nanoscopic dynamics. Corroborated by acoustic wave simulation, the role of defects in forming even harmonics is elucidated. Above the Néel temperature (TN), the interlayer shear acoustic harmonics are suppressed, while the in-plane traveling wave is predominantly excited. The dominant acoustic dynamics shifts from the out-of-plane shear to the in-plane traveling wave across TN, demonstrating that magnetic properties can influence phonon scattering pathways. The spatiotemporally resolved structural characterization provides valuable nanoscopic insights for interlayer-shear-mode-based acoustic cavities, opening up possibilities for magneto-mechanical applications of vdW magnets.
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Affiliation(s)
- Faran Zhou
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Haihua Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Marc Zajac
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kyle Hwangbo
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Qianni Jiang
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Ilke Arslan
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Thomas E Gage
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Haidan Wen
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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5
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Mazor Y, Kfir O. Sub-terahertz nearfields for electron-pulse compression. OPTICS EXPRESS 2023; 31:37980-37992. [PMID: 38017916 DOI: 10.1364/oe.502407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/02/2023] [Indexed: 11/30/2023]
Abstract
The advent of ultrafast science with pulsed electron beams raised the need to control the temporal features of the electron pulses. One promising suggestion is the nano-selective quantum optics with multi-electrons, which scales quadratically with the number of electrons within the coherence time of the quantum system. Terahertz (THz) radiation from optical nonlinear crystals is an attractive methodology to generate the rapidly varying electric fields necessary for electron compression, with the advantage of an inherent temporal locking to laser-triggered electrons, such as in ultrafast electron microscopes. Longer (picosecond-) pulses require a sub-THz field for their compression. However, the generation of such low frequencies requires pumping with energetic optical pulses and their focusability is fundamentally limited by their mm-wavelength. This work proposes electron-pulse compression with sub-THz fields directly in the vicinity of their dipolar origin, thereby avoiding mediation through radiation. We analyze the merits of nearfields for compression of slow electrons, particularly in challenging regimes for THz radiation, such as small numerical apertures, micro-joule-level optical pump pulses, and low frequencies. This scheme can be implemented within the tight constraints of electron microscopes and reach fields of a few kV/cm below 0.1 THz at high repetition rates. Our paradigm offers a realistic approach for controlling electron pulses spatially and temporally in many experiments, opening the path of flexible multi-electron manipulation for analytic and quantum sciences.
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6
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Yannai M, Adiv Y, Dahan R, Wang K, Gorlach A, Rivera N, Fishman T, Krüger M, Kaminer I. Lossless Monochromator in an Ultrafast Electron Microscope Using Near-Field THz Radiation. PHYSICAL REVIEW LETTERS 2023; 131:145002. [PMID: 37862634 DOI: 10.1103/physrevlett.131.145002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/03/2023] [Accepted: 08/21/2023] [Indexed: 10/22/2023]
Abstract
The ability to form monoenergetic electron beams is vital for high-resolution electron spectroscopy and imaging. Such capabilities are commonly achieved using an electron monochromator, which energy filters a dispersed electron beam, thus reducing the electron flux to yield down to meV energy resolution. This reduction in flux hinders the use of monochromators in many applications, such as ultrafast transmission electron microscopes (UTEMs). Here, we develop and demonstrate a mechanism for electron energy monochromation that does not reduce the flux-a lossless monochromator. The mechanism is based on the interaction of free-electron pulses with single-cycle THz near fields, created by nonlinear conversion of an optical laser pulse near the electron beam path inside a UTEM. Our experiment reduces the electron energy spread by a factor of up to 2.9 without compromising the beam flux. Moreover, as the electron-THz interaction takes place over an extended region of many tens of microns in free space, the realized technique is highly robust-granting uniform monochromation over a wide area, larger than the electron beam diameter. We further demonstrate the wide tunability of our method by monochromating the electron beam at multiple primary electron energies from 60 to 200 keV, studying the effect of various electron and THz parameters on its performance. Our findings have direct applications in the fast-growing field of ultrafast electron microscopy, allowing time- and energy-resolved studies of exciton physics, phononic vibrational resonances, charge transport effects, and optical excitations in the mid IR to the far IR.
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Affiliation(s)
- Michael Yannai
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yuval Adiv
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Raphael Dahan
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Kangpeng Wang
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201815, China
| | - Alexey Gorlach
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Nicholas Rivera
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Tal Fishman
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Michael Krüger
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Department of Physics, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ido Kaminer
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
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7
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Holstad TS, Dresselhaus-Marais LE, Ræder TM, Kozioziemski B, van Driel T, Seaberg M, Folsom E, Eggert JH, Knudsen EB, Nielsen MM, Simons H, Haldrup K, Poulsen HF. Real-time imaging of acoustic waves in bulk materials with X-ray microscopy. Proc Natl Acad Sci U S A 2023; 120:e2307049120. [PMID: 37725646 PMCID: PMC10523471 DOI: 10.1073/pnas.2307049120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/07/2023] [Indexed: 09/21/2023] Open
Abstract
The dynamics of lattice vibrations govern many material processes, such as acoustic wave propagation, displacive phase transitions, and ballistic thermal transport. The maximum velocity of these processes and their effects is determined by the speed of sound, which therefore defines the temporal resolution (picoseconds) needed to resolve these phenomena on their characteristic length scales (nanometers). Here, we present an X-ray microscope capable of imaging acoustic waves with subpicosecond resolution within mm-sized crystals. We directly visualize the generation, propagation, branching, and energy dissipation of longitudinal and transverse acoustic waves in diamond, demonstrating how mechanical energy thermalizes from picosecond to microsecond timescales. Bulk characterization techniques capable of resolving this level of structural detail have previously been available on millisecond time scales-orders of magnitude too slow to capture these fundamental phenomena in solid-state physics and geoscience. As such, the reported results provide broad insights into the interaction of acoustic waves with the structure of materials, and the availability of ultrafast time-resolved dark-field X-ray microscopy opens a vista of new opportunities for 3D imaging of materials dynamics on their intrinsic submicrosecond time scales.
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Affiliation(s)
- Theodor S. Holstad
- Department of Physics, Technical University of Denmark, Kongens Lyngby2800, Denmark
| | - Leora E. Dresselhaus-Marais
- Department of Materials Science & Engineering, Stanford University, Stanford, CA94305
- SLAC National Accelerator Laboratory, Menlo Park, CA94025-7015
- Physics Division, Lawrence Livermore National Laboratory, Livermore, CA94550-9234
| | - Trygve Magnus Ræder
- Department of Physics, Technical University of Denmark, Kongens Lyngby2800, Denmark
| | - Bernard Kozioziemski
- Physics Division, Lawrence Livermore National Laboratory, Livermore, CA94550-9234
| | - Tim van Driel
- SLAC National Accelerator Laboratory, Menlo Park, CA94025-7015
| | - Matthew Seaberg
- SLAC National Accelerator Laboratory, Menlo Park, CA94025-7015
| | - Eric Folsom
- Physics Division, Lawrence Livermore National Laboratory, Livermore, CA94550-9234
| | - Jon H. Eggert
- Physics Division, Lawrence Livermore National Laboratory, Livermore, CA94550-9234
| | | | | | - Hugh Simons
- Department of Physics, Technical University of Denmark, Kongens Lyngby2800, Denmark
| | - Kristoffer Haldrup
- Department of Physics, Technical University of Denmark, Kongens Lyngby2800, Denmark
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8
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Zong A, Zhang Q, Zhou F, Su Y, Hwangbo K, Shen X, Jiang Q, Liu H, Gage TE, Walko DA, Kozina ME, Luo D, Reid AH, Yang J, Park S, Lapidus SH, Chu JH, Arslan I, Wang X, Xiao D, Xu X, Gedik N, Wen H. Spin-mediated shear oscillators in a van der Waals antiferromagnet. Nature 2023; 620:988-993. [PMID: 37532936 DOI: 10.1038/s41586-023-06279-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/02/2023] [Indexed: 08/04/2023]
Abstract
Understanding how microscopic spin configuration gives rise to exotic properties at the macroscopic length scale has long been pursued in magnetic materials1-5. One seminal example is the Einstein-de Haas effect in ferromagnets1,6,7, in which angular momentum of spins can be converted into mechanical rotation of an entire object. However, for antiferromagnets without net magnetic moment, how spin ordering couples to macroscopic movement remains elusive. Here we observed a seesaw-like rotation of reciprocal lattice peaks of an antiferromagnetic nanolayer film, whose gigahertz structural resonance exhibits more than an order-of-magnitude amplification after cooling below the Néel temperature. Using a suite of ultrafast diffraction and microscopy techniques, we directly visualize this spin-driven rotation in reciprocal space at the nanoscale. This motion corresponds to interlayer shear in real space, in which individual micro-patches of the film behave as coherent oscillators that are phase-locked and shear along the same in-plane axis. Using time-resolved optical polarimetry, we further show that the enhanced mechanical response strongly correlates with ultrafast demagnetization, which releases elastic energy stored in local strain gradients to drive the oscillators. Our work not only offers the first microscopic view of spin-mediated mechanical motion of an antiferromagnet but it also identifies a new route towards realizing high-frequency resonators8,9 up to the millimetre band, so the capability of controlling magnetic states on the ultrafast timescale10-13 can be readily transferred to engineering the mechanical properties of nanodevices.
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Affiliation(s)
- Alfred Zong
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Qi Zhang
- Department of Physics, University of Washington, Seattle, WA, USA
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
- Department of Physics, Nanjing University, Nanjing, China
| | - Faran Zhou
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Yifan Su
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kyle Hwangbo
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Qianni Jiang
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Haihua Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Thomas E Gage
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Donald A Walko
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | | | - Duan Luo
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | | | - Jie Yang
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Suji Park
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA
| | - Saul H Lapidus
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Ilke Arslan
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Di Xiao
- Department of Physics, University of Washington, Seattle, WA, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA, USA.
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA.
| | - Nuh Gedik
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Haidan Wen
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA.
- Materials Science Division, Argonne National Laboratory, Lemont, IL, USA.
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9
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Reisbick SA, Zhu Y. Artifact Elimination in Ultrafast Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:435-436. [PMID: 37613579 DOI: 10.1093/micmic/ozad067.206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Spencer A Reisbick
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
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10
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Willis SA, Flannigan DJ. Stable Photoemission from the Wehnelt Aperture Surface in 4D Ultrafast Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1842-1844. [PMID: 37612902 DOI: 10.1093/micmic/ozad067.1103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Simon A Willis
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, United States
- Minnesota Institute of Ultrafast Science, University of Minnesota, Minneapolis, MN, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, United States
- Minnesota Institute of Ultrafast Science, University of Minnesota, Minneapolis, MN, United States
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11
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Alcorn FM, van der Veen RM, Jain PK. In Situ Electron Microscopy of Transformations of Copper Nanoparticles under Plasmonic Excitation. NANO LETTERS 2023. [PMID: 37399502 DOI: 10.1021/acs.nanolett.3c01474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
Metal nanoparticles are attracting interest for their light-absorption properties, but such materials are known to dynamically evolve under the action of chemical and physical perturbations, resulting in changes in their structure and composition. Using a transmission electron microscope equipped for optical excitation of the specimen, the structural evolution of Cu-based nanoparticles under simultaneous electron beam irradiation and plasmonic excitation was investigated with high spatiotemporal resolution. These nanoparticles initially have a Cu core-Cu2O oxide shell structure, but over the course of imaging, they undergo hollowing via the nanoscale Kirkendall effect. We captured the nucleation of a void within the core, which then rapidly grows along specific crystallographic directions until the core is hollowed out. Hollowing is triggered by electron-beam irradiation; plasmonic excitation enhances the kinetics of the transformation likely by the effect of photothermal heating.
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Affiliation(s)
- Francis M Alcorn
- Department of Chemistry, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
| | - Renske M van der Veen
- Department of Chemistry, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
| | - Prashant K Jain
- Department of Chemistry, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
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12
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Reisbick SA, Pofelski A, Han MG, Liu C, Montgomery E, Jing C, Sawada H, Zhu Y. Characterization of transverse electron pulse trains using RF powered traveling wave metallic comb striplines. Ultramicroscopy 2023; 249:113733. [PMID: 37030159 DOI: 10.1016/j.ultramic.2023.113733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 02/20/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023]
Abstract
Advancements in ultrafast electron microscopy have allowed elucidation of spatially selective structural dynamics. However, as the spatial resolution and imaging capabilities have made progress, quantitative characterization of the electron pulse trains has not been reported at the same rate. In fact, inexperienced users have difficulty replicating the technique because only a few dedicated microscopes have been characterized thoroughly. Systems replacing laser driven photoexcitation with electrically driven deflectors especially suffer from a lack of quantified characterization because of the limited quantity. The primary advantages to electrically driven systems are broader frequency ranges, ease of use and simple synchronization to electrical pumping. Here, we characterize the technical parameters for electrically driven UEM including the shape, size and duration of the electron pulses using low and high frequency chopping methods. At high frequencies, pulses are generated by sweeping the electron beam across a chopping aperture. For low frequencies, the beam is continuously forced off the optic axis by a DC potential, then momentarily aligned by a countering pulse. Using both methods, we present examples that measure probe durations of 2 ns and 10 ps for the low and high frequency techniques, respectively. We also discuss how the implementation of a pulsed probe affects STEM imaging conditions by adjusting the first condenser lens.
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13
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Nakamura A, Shimojima T, Ishizaka K. Characterizing an Optically Induced Sub-micrometer Gigahertz Acoustic Wave in a Silicon Thin Plate. NANO LETTERS 2023; 23:2490-2495. [PMID: 36944354 PMCID: PMC10103304 DOI: 10.1021/acs.nanolett.2c03938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Optically induced GHz-THz guided acoustic waves have been intensively studied because of the potential to realize noninvasive and noncontact material inspection. Although the generation of photoinduced guided acoustic waves utilizing nanostructures, such as ultrathin plates, nanowires, and materials interfaces, is being established, experimental characterization of these acoustic waves in consideration of the finite size effect has been difficult due to the lack of experimental methods with nm × ps resolution. Here we experimentally observe the sub-micrometer guided acoustic waves in a nanofabricated ultrathin silicon plate by ultrafast transmission electron microscopy with nm × ps precision. We successfully characterize the excited guided acoustic wave in frequency-wavenumber space by applying Fourier-transformation analysis on the bright-field movie. These results suggest the great potential of ultrafast transmission electron microscopy to characterize the acoustic modes realized in various nanostructures.
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Affiliation(s)
- Asuka Nakamura
- RIKEN
Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | | | - Kyoko Ishizaka
- RIKEN
Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
- Quantum-Phase
Electronics Center and Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
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14
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Wang L, Ma M, Wang H, Xiong H, Chen X, Wei F, Shen B. Real-Space Imaging of the Molecular Changes in Metal-Organic Frameworks under Electron Irradiation. ACS NANO 2023; 17:4740-4747. [PMID: 36811555 DOI: 10.1021/acsnano.2c11110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Electron-induced structural changes influence the characterizations of the local structure of various materials by electron microscope. However, for beam-sensitive materials, it is still challenging to detect such changes by electron microscopy, which may help us quantitatively reveal how electrons interact with materials under electron irradiation. Here, we use an emergent phase contrast technique in electron microscopy to clearly image a metal-organic framework, UiO-66 (Zr), at an ultralow electron dose and dose rate. The effects of both the dose and dose rate on the UiO-66 (Zr) structure are visualized, which induce obvious missing organic linkers. The kinetics of the missing linker based on the radiolysis mechanism are semiquantitatively expressed by the different intensities of the imaged organic linkers. Deformation of the UiO-66 (Zr) lattice after the missing linker is also observed. These observations make it possible to visually investigate the electron-induced chemistry in various beam-sensitive materials and avoid electron damage to them.
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Affiliation(s)
- Lei Wang
- Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, PR China
- Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, Jiangsu, PR China
| | - Mengmeng Ma
- Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, PR China
- Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, Jiangsu, PR China
| | - Huiqiu Wang
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China
| | - Hao Xiong
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China
| | - Xiao Chen
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China
| | - Fei Wei
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China
| | - Boyuan Shen
- Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, PR China
- Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, Jiangsu, PR China
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15
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Yannai M, Dahan R, Gorlach A, Adiv Y, Wang K, Madan I, Gargiulo S, Barantani F, Dias EJC, Vanacore GM, Rivera N, Carbone F, García de Abajo FJ, Kaminer I. Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors. ACS NANO 2023; 17:3645-3656. [PMID: 36736033 DOI: 10.1021/acsnano.2c10481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The ultrafast dynamics of charge carriers in solids plays a pivotal role in emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, the investigation and direct visualization of such nonequilibrium phenomena remains as a long-standing challenge, owing to the nanometer-femtosecond spatiotemporal scales at which the charge carriers evolve. Here, we propose and demonstrate an interaction mechanism enabling nanoscale imaging of the femtosecond dynamics of charge carriers in solids. This imaging modality, which we name charge dynamics electron microscopy (CDEM), exploits the strong interaction of free-electron pulses with terahertz (THz) near fields produced by the moving charges in an ultrafast scanning transmission electron microscope. The measured free-electron energy at different spatiotemporal coordinates allows us to directly retrieve the THz near-field amplitude and phase, from which we reconstruct movies of the generated charges by comparison to microscopic theory. The CDEM technique thus allows us to investigate previously inaccessible spatiotemporal regimes of charge dynamics in solids, providing insight into the photo-Dember effect and showing oscillations of photogenerated electron-hole distributions inside a semiconductor. Our work facilitates the exploration of a wide range of previously inaccessible charge-transport phenomena in condensed matter using ultrafast electron microscopy.
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Affiliation(s)
- Michael Yannai
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Raphael Dahan
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Alexey Gorlach
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yuval Adiv
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Kangpeng Wang
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ivan Madan
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - Simone Gargiulo
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - Francesco Barantani
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Eduardo J C Dias
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Giovanni Maria Vanacore
- Department of Materials Science, University of Milano-Bicocca, Via Cozzi 55, 20121 Milano, Italy
| | - Nicholas Rivera
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Fabrizio Carbone
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 6, Lausanne 1015, Switzerland
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Ido Kaminer
- Technion - Israel Institute of Technology, Haifa 3200003, Israel
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16
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Time-resolved transmission electron microscopy for nanoscale chemical dynamics. Nat Rev Chem 2023; 7:256-272. [PMID: 37117417 DOI: 10.1038/s41570-023-00469-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2023] [Indexed: 02/24/2023]
Abstract
The ability of transmission electron microscopy (TEM) to image a structure ranging from millimetres to Ångströms has made it an indispensable component of the toolkit of modern chemists. TEM has enabled unprecedented understanding of the atomic structures of materials and how structure relates to properties and functions. Recent developments in TEM have advanced the technique beyond static material characterization to probing structural evolution on the nanoscale in real time. Accompanying advances in data collection have pushed the temporal resolution into the microsecond regime with the use of direct-electron detectors and down to the femtosecond regime with pump-probe microscopy. Consequently, studies have deftly applied TEM for understanding nanoscale dynamics, often in operando. In this Review, time-resolved in situ TEM techniques and their applications for probing chemical and physical processes are discussed, along with emerging directions in the TEM field.
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17
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Tong L, Yuan J, Zhang Z, Tang J, Wang Z. Nanoscale subparticle imaging of vibrational dynamics using dark-field ultrafast transmission electron microscopy. NATURE NANOTECHNOLOGY 2023; 18:145-152. [PMID: 36509924 DOI: 10.1038/s41565-022-01255-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 10/04/2022] [Indexed: 06/17/2023]
Abstract
An understanding of nanoscale energy transport and acoustic response is important for applications of nanomaterials but hinges on a complete characterization of their structural dynamics. The precise determination of the structural dynamics within nanoparticles, however, is still challenging and requires high spatiotemporal resolution and detection sensitivity. Here we present a centred dark-field imaging approach based on ultrafast transmission electron microscopy that is capable of directly mapping the picosecond-scale evolution of intrananoparticle vibration with a spatial resolution down to 3 nm. Using this approach, we investigated the photo-induced vibrational dynamics in individual gold heterodimers composed of a nanoprism and a nanosphere. We observed not only the retardation of in-plane vibrations in the nanoprisms, which we attribute to thermal and vibrational energy transferred from adjacent nanospheres mediated by surfactants, but also the existence of a complex multimodal oscillation and its spatial variation within individual nanoprisms. This work represents an advance in real-space mapping of vibrational dynamics on the subnanoparticle level with a high detection sensitivity.
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Affiliation(s)
- Ling Tong
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, People's Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jun Yuan
- School of Physics, Engineering and Technology, University of York, York, UK
| | - Zhiwei Zhang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, People's Republic of China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jau Tang
- The Institute for Technological Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Zhiwei Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, People's Republic of China.
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, People's Republic of China.
- Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning, People's Republic of China.
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18
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Shimojima T, Nakamura A, Ishizaka K. Development of five-dimensional scanning transmission electron microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:023705. [PMID: 36859021 DOI: 10.1063/5.0106517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
By combining the scanning transmission electron microscopy with the ultrafast optical pump-probe technique, we improved the time resolution by a factor of ∼1012 for the differential phase contrast and convergent-beam electron diffraction imaging. These methods provide ultrafast nanoscale movies of physical quantities in nano-materials, such as crystal lattice deformation, magnetization vector, and electric field. We demonstrate the observations of the photo-induced acoustic phonon propagation with an accuracy of 4 ps and 8 nm and the ultrafast demagnetization under zero magnetic field with 10 ns and 400 nm resolution, by utilizing these methods.
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Affiliation(s)
- T Shimojima
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - A Nakamura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - K Ishizaka
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
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19
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Kim YJ, Nho HW, Ji S, Lee H, Ko H, Weissenrieder J, Kwon OH. Femtosecond-resolved imaging of a single-particle phase transition in energy-filtered ultrafast electron microscopy. SCIENCE ADVANCES 2023; 9:eadd5375. [PMID: 36706188 PMCID: PMC9882981 DOI: 10.1126/sciadv.add5375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 12/20/2022] [Indexed: 06/18/2023]
Abstract
Using an energy filter in transmission electron microscopy has enabled elemental mapping at the atomic scale and improved the precision of structural determination by gating inelastic and elastic imaging electrons, respectively. Here, we use an energy filter in ultrafast electron microscopy to enhance the temporal resolution toward the domain of atomic motion. Visualizing transient structures with femtosecond temporal precision was achieved by selecting imaging electrons in a narrow energy distribution from dense chirped photoelectron packets with broad longitudinal momentum distributions and thus typically exhibiting picosecond durations. In this study, the heterogeneous ultrafast phase transitions of vanadium dioxide (VO2) nanoparticles, a representative strongly correlated system, were filmed and attributed to the emergence of a transient, low-symmetry metallic phase caused by different local strains. Our approach enables electron microscopy to access the time scale of elementary nuclear motion to visualize the onset of the structural dynamics of matter at the nanoscale.
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Affiliation(s)
- Ye-Jin Kim
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hak-Won Nho
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Shaozheng Ji
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Hyejin Lee
- School of Energy and Chemical Engineering, UNIST, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hyunhyub Ko
- School of Energy and Chemical Engineering, UNIST, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Jonas Weissenrieder
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Oh-Hoon Kwon
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science, 50 UNIST-gil, Ulsan 44919, Republic of Korea
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20
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Ji S, Grånäs O, Kumar Prasad A, Weissenrieder J. Influence of strain on an ultrafast phase transition. NANOSCALE 2022; 15:304-312. [PMID: 36484465 PMCID: PMC9773179 DOI: 10.1039/d2nr03395j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
The flexibility of 2D materials combined with properties highly sensitive to strain makes strain engineering a promising avenue for manipulation of both structure and function. Here we investigate the influence of strain, associated with microstructural defects, on a photo-induced structural phase transition in Td-WTe2. Above threshold photoexcitation of uniform, non-strained, samples result in an orthorhombic Td to a metastable orthorhombic 1T* phase transition facilitated by shear displacements of the WTe2 layers along the b axis of the material. In samples prepared with wrinkle defects WTe2 continue its trajectory through a secondary transition that shears the unit cell along the c axis towards a metastable monoclinic 1T' phase. The time scales and microstructural evolution associated with the transition and its subsequent recovery to the 1T* phase is followed in detail by a combination of ultrafast electron diffraction and microscopy. Our findings show how local strain fields can be employed for tailoring phase change dynamics in ultrafast optically driven processes with potential applications in phase change devices.
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Affiliation(s)
- Shaozheng Ji
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
- Ultrafast Electron Microscopy Laboratory, The MOE Key Laboratory of Weak-Light Nonlinear Photonics, School of Physics, Nankai University, Tianjin 300071, China
| | - Oscar Grånäs
- Materials Theory, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Amit Kumar Prasad
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Jonas Weissenrieder
- Materials and Nano Physics, School of Engineering Sciences, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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21
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Picher M, Sinha SK, LaGrange T, Banhart F. Analytics at the nanometer and nanosecond scales by short electron pulses in an electron microscope. CHEMTEXTS 2022. [DOI: 10.1007/s40828-022-00169-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Nakamura A, Shimojima T, Ishizaka K. Visualizing optically-induced strains by five-dimensional ultrafast electron microscopy. Faraday Discuss 2022; 237:27-39. [PMID: 35661182 DOI: 10.1039/d2fd00062h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultrafast optical control of strain is crucial for the future development of nanometric acoustic devices. Although ultrafast electron microscopy has played an important role in the visualization of strain dynamics in the GHz frequency region, quantitative strain evaluation with nm × ps spatio-temporal resolution is still challenging. Five-dimensional scanning transmission electron microscopy (5D-STEM) is a powerful technique that measures time-dependent diffraction or deflection of the electron beam at the respective two-dimensional sample positions in real space. In this paper, we demonstrate that convergent beam electron diffraction (CBED) measurements using 5D-STEM are capable of quantitative time-dependent strain mapping in the nm × ps scale. We observe the generation and propagation of acoustic waves in a nanofabricated silicon thin plate of 100 nm thickness. The polarization and amplitude of the acoustic waves propagating in the silicon plate are quantitatively determined from the CBED analysis. Further Fourier-transformation analysis reveals the strain distribution in the momentum-frequency space, which gives the dispersion relation in arbitrary directions along the plate. Versatility of 5D-STEM-CBED analysis enables quantitative strain mapping even in complex nanofabricated samples, as demonstrated in this study.
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Affiliation(s)
- A Nakamura
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan.
| | - T Shimojima
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan.
| | - K Ishizaka
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan. .,Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
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23
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Curtis WA, Willis SA, Flannigan DJ. Single-photoelectron collection efficiency in 4D ultrafast electron microscopy. Phys Chem Chem Phys 2022; 24:14044-14054. [PMID: 35640169 DOI: 10.1039/d2cp01250b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In femtosecond (fs) 4D ultrafast electron microscopy (UEM), a tradeoff is made between photoelectrons per packet and time resolution. One consequence of this can be longer-than-desirable acquisition times for low-density packets, and particularly for low repetition rates when complete photothermal dissipation is required. Thus, gaining an understanding of photoelectron trajectories in the gun region is important for identifying factors that limit collection efficiency (CE; fraction of photoelectrons that enter the illumination system). Here, we continue our work on the systematic study of photoelectron trajectories in the gun region of a Thermo Fisher/FEI Tecnai Femto UEM, focusing specifically on CE in the single-electron regime. Using General Particle Tracer, calculated field maps, and the exact architecture of the Tecnai Femto UEM, we simulated the effects of fs laser parameters and key gun elements on CE. The results indicate CE strongly depends upon the laser spot size on the source, the (unbiased) Wehnelt aperture diameter, and the incident photon energy. The CE dispersion with laser spot size is found to be strongly dependent on aperture diameter, being nearly dispersionless for the largest apertures. A gun crossover is also observed, with the beam-waist position being dependent on the aperture diameter, further illustrating that the Wehnelt aperture acts as a simple, fixed electrostatic lens in UEM mode. This work provides further insights into the operational aspects of fs 4D UEM.
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Affiliation(s)
- Wyatt A Curtis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Simon A Willis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
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24
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Ahn Y, Cherukara MJ, Cai Z, Bartlein M, Zhou T, DiChiara A, Walko DA, Holt M, Fullerton EE, Evans PG, Wen H. X-ray nanodiffraction imaging reveals distinct nanoscopic dynamics of an ultrafast phase transition. Proc Natl Acad Sci U S A 2022; 119:e2118597119. [PMID: 35522708 PMCID: PMC9171639 DOI: 10.1073/pnas.2118597119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/11/2022] [Indexed: 12/04/2022] Open
Abstract
SignificancePhase transitions, the changes between states of matter with distinct electronic, magnetic, or structural properties, are at the center of condensed matter physics and underlie valuable technologies. First-order phase transitions are intrinsically heterogeneous. When driven by ultrashort excitation, nanoscale phase regions evolve rapidly, which has posed a significant experimental challenge to characterize. The newly developed laser-pumped X-ray nanodiffraction imaging technique reported here has simultaneous 100-ps temporal and 25-nm spatial resolutions. This approach reveals pathways of the nanoscale structural rearrangement upon ultrafast optical excitation, different from those transitions under slowly varying parameters. The spatiotemporally resolved structural characterization provides crucial nanoscopic insights into ultrafast phase transitions and opens opportunities for controlling nanoscale phases on ultrafast time scales.
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Affiliation(s)
- Youngjun Ahn
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
- Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706
| | - Mathew J. Cherukara
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL 60439
| | - Zhonghou Cai
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
| | - Michael Bartlein
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL 60439
| | - Tao Zhou
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL 60439
| | - Anthony DiChiara
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
| | - Donald A. Walko
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
| | - Martin Holt
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL 60439
| | - Eric E. Fullerton
- Center for Magnetic Recording Research, University of California San Diego, La Jolla, CA 92903
| | - Paul G. Evans
- Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706
| | - Haidan Wen
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439
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25
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Li WH, Duncan CJR, Andorf MB, Bartnik AC, Bianco E, Cultrera L, Galdi A, Gordon M, Kaemingk M, Pennington CA, Kourkoutis LF, Bazarov IV, Maxson JM. A kiloelectron-volt ultrafast electron micro-diffraction apparatus using low emittance semiconductor photocathodes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2022; 9:024302. [PMID: 35350376 PMCID: PMC8934190 DOI: 10.1063/4.0000138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/16/2022] [Indexed: 06/12/2023]
Abstract
We report the design and performance of a time-resolved electron diffraction apparatus capable of producing intense bunches with simultaneously single digit micrometer probe size, long coherence length, and 200 fs rms time resolution. We measure the 5d (peak) beam brightness at the sample location in micro-diffraction mode to be 7 × 10 13 A / m 2 rad 2 . To generate high brightness electron bunches, the system employs high efficiency, low emittance semiconductor photocathodes driven with a wavelength near the photoemission threshold at a repetition rate up to 250 kHz. We characterize spatial, temporal, and reciprocal space resolution of the apparatus. We perform proof-of-principle measurements of ultrafast heating in single crystal Au samples and compare experimental results with simulations that account for the effects of multiple scattering.
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Affiliation(s)
- W. H. Li
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - C. J. R. Duncan
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - M. B. Andorf
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - A. C. Bartnik
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - E. Bianco
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - L. Cultrera
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - A. Galdi
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - M. Gordon
- University of Chicago, Chicago, Illinois 60637, USA
| | - M. Kaemingk
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - C. A. Pennington
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | | | - I. V. Bazarov
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - J. M. Maxson
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
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26
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Holstad TS, Ræder TM, Carlsen M, Bergbäck Knudsen E, Dresselhaus-Marais L, Haldrup K, Simons H, Nielsen MM, Poulsen HF. X-ray free-electron laser based dark-field X-ray microscopy: a simulation-based study. J Appl Crystallogr 2022. [DOI: 10.1107/s1600576721012760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Dark-field X-ray microscopy (DFXM) is a nondestructive full-field imaging technique providing three-dimensional mapping of microstructure and local strain fields in deeply embedded crystalline elements. This is achieved by placing an objective lens in the diffracted beam, giving a magnified projection image. So far, the method has been applied with a time resolution of milliseconds to hours. In this work, the feasibility of DFXM at the picosecond time scale using an X-ray free-electron laser source and a pump–probe scheme is considered. Thermomechanical strain-wave simulations are combined with geometrical optics and wavefront propagation optics to simulate DFXM images of phonon dynamics in a diamond single crystal. Using the specifications of the XCS instrument at the Linac Coherent Light Source as an example results in simulated DFXM images clearly showing the propagation of a strain wave.
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27
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Zhang Y, Choi MK, Haugstad G, Tadmor EB, Flannigan DJ. Holey Substrate-Directed Strain Patterning in Bilayer MoS 2. ACS NANO 2021; 15:20253-20260. [PMID: 34780160 DOI: 10.1021/acsnano.1c08348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Key properties of two-dimensional (2D) layered materials are highly strain tunable, arising from bond modulation and associated reconfiguration of the energy bands around the Fermi level. Approaches to locally controlling and patterning strain have included both active and passive elastic deformation via sustained loading and templating with nanostructures. Here, by float-capturing ultrathin flakes of single-crystal 2H-MoS2 on amorphous holey silicon nitride substrates, we find that highly symmetric, high-fidelity strain patterns are formed. The hexagonally arranged holes and surface topography combine to generate highly conformal flake-substrate coverage creating patterns that match optimal centroidal Voronoi tessellation in 2D Euclidean space. Using TEM imaging and diffraction, as well as AFM topographic mapping, we determine that the substrate-driven 3D geometry of the flakes over the holes consists of symmetric, out-of-plane bowl-like deformation of up to 35 nm, with in-plane, isotropic tensile strains of up to 1.8% (measured with both selected-area diffraction and AFM). Atomistic and image simulations accurately predict spontaneous formation of the strain patterns, with van der Waals forces and substrate topography as the input parameters. These results show that predictable patterns and 3D topography can be spontaneously induced in 2D materials captured on bare, holey substrates. The method also enables electron scattering studies of precisely aligned, substrate-free strained regions in transmission mode.
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Affiliation(s)
- Yichao Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Moon-Ki Choi
- Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Greg Haugstad
- Characterization Facility, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ellad B Tadmor
- Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Abstract
Implementing the modern technologies of light-emitting devices, light harvesting, and quantum information processing requires the understanding of the structure-function relations at spatial scales below the optical diffraction limit and time scales of energy and information flows. Here, we distinctively combine cathodoluminescence (CL) with ultrafast electron microscopy (UEM), termed CL-UEM, because CL and UEM synergetically afford the required spectral and spatiotemporal sensitivities, respectively. For color centers in nanodiamonds, we demonstrate the measurement of CL lifetime with a local sensitivity of 50 nm and a time resolution of 100 ps. It is revealed that the emitting states of the color centers can be populated through charge transfer among the color centers across diamond lattices upon high-energy electron beam excitation. The technical advance achieved in this study will facilitate the specific control over energy conversion at nanoscales, relevant to quantum dots and single-photon sources.
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Affiliation(s)
- Ye-Jin Kim
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Korea
| | - Oh-Hoon Kwon
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Korea
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29
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Henke JW, Raja AS, Feist A, Huang G, Arend G, Yang Y, Kappert FJ, Wang RN, Möller M, Pan J, Liu J, Kfir O, Ropers C, Kippenberg TJ. Integrated photonics enables continuous-beam electron phase modulation. Nature 2021; 600:653-658. [PMID: 34937900 PMCID: PMC8695378 DOI: 10.1038/s41586-021-04197-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 11/01/2021] [Indexed: 11/10/2022]
Abstract
Integrated photonics facilitates extensive control over fundamental light-matter interactions in manifold quantum systems including atoms1, trapped ions2,3, quantum dots4 and defect centres5. Ultrafast electron microscopy has recently made free-electron beams the subject of laser-based quantum manipulation and characterization6-11, enabling the observation of free-electron quantum walks12-14, attosecond electron pulses10,15-17 and holographic electromagnetic imaging18. Chip-based photonics19,20 promises unique applications in nanoscale quantum control and sensing but remains to be realized in electron microscopy. Here we merge integrated photonics with electron microscopy, demonstrating coherent phase modulation of a continuous electron beam using a silicon nitride microresonator. The high-finesse (Q0 ≈ 106) cavity enhancement and a waveguide designed for phase matching lead to efficient electron-light scattering at extremely low, continuous-wave optical powers. Specifically, we fully deplete the initial electron state at a cavity-coupled power of only 5.35 microwatts and generate >500 electron energy sidebands for several milliwatts. Moreover, we probe unidirectional intracavity fields with microelectronvolt resolution in electron-energy-gain spectroscopy21. The fibre-coupled photonic structures feature single-optical-mode electron-light interaction with full control over the input and output light. This approach establishes a versatile and highly efficient framework for enhanced electron beam control in the context of laser phase plates22, beam modulators and continuous-wave attosecond pulse trains23, resonantly enhanced spectroscopy24-26 and dielectric laser acceleration19,20,27. Our work introduces a universal platform for exploring free-electron quantum optics28-31, with potential future developments in strong coupling, local quantum probing and electron-photon entanglement.
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Affiliation(s)
- Jan-Wilke Henke
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Arslan Sajid Raja
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Armin Feist
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Guanhao Huang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Germaine Arend
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Yujia Yang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - F Jasmin Kappert
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Rui Ning Wang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Marcel Möller
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Jiahe Pan
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Junqiu Liu
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Ofer Kfir
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Claus Ropers
- Georg-August-Universität Göttingen, Göttingen, Germany.
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany.
| | - Tobias J Kippenberg
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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30
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Inoue T, Junpei Y, Itoh S, Okuda T, Funahashi A, Takimoto T, Kakue T, Nishio K, Matoba O, Awatsuji Y. Spatiotemporal observation of light propagation in a three-dimensional scattering medium. Sci Rep 2021; 11:21890. [PMID: 34750419 PMCID: PMC8576009 DOI: 10.1038/s41598-021-01124-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/18/2021] [Indexed: 11/10/2022] Open
Abstract
Spatiotemporal information about light pulse propagation obtained with femtosecond temporal resolution plays an important role in understanding transient phenomena and light–matter interactions. Although ultrafast optical imaging techniques have been developed, it is still difficult to capture light pulse propagation spatiotemporally. Furthermore, imaging through a three-dimensional (3-D) scattering medium is a longstanding challenge due to the optical scattering caused by the interaction between light pulse and a 3-D scattering medium. Here, we propose a technique for ultrafast optical imaging of light pulses propagating inside a 3D scattering medium. We record an image of the light pulse propagation using the ultrashort light pulse even when the interaction between light pulse and a 3-D scattering medium causes the optical scattering. We demonstrated our proposed technique by recording converging, refracted, and diffracted propagating light for 59 ps with femtosecond temporal resolution.
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Affiliation(s)
- Tomoyoshi Inoue
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.,Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan
| | - Yuasa Junpei
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Seiya Itoh
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Tatsuya Okuda
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Akinori Funahashi
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Tetsuya Takimoto
- Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Takashi Kakue
- Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Kenzo Nishio
- Advanced Technology Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Osamu Matoba
- Organization for Advanced and Integrated Research, Kobe University, Rokkodai 1-1, Nada, Kobe, 657-850, Japan
| | - Yasuhiro Awatsuji
- Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
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31
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Curtis WA, Flannigan DJ. Toward Å-fs-meV resolution in electron microscopy: systematic simulation of the temporal spread of single-electron packets. Phys Chem Chem Phys 2021; 23:23544-23553. [PMID: 34648611 DOI: 10.1039/d1cp03518e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Though efforts to improve the temporal resolution of transmission electron microscopes (TEMs) have waxed and waned for decades, with relatively recent advances routinely reaching sub-picosecond scales, fundamental and practical challenges have hindered the advance of combined Å-fs-meV resolutions, particularly for core-loss spectroscopy and real-space imaging. This is due in no small part to the complexity of the approach required to access timescales upon which electrons, atoms, molecules, and materials first begin to respond and transform - attoseconds to picoseconds. Here we present part of a larger effort devoted to systematically mapping the instrument parameter space of a TEM modified to reach ultrafast timescales. With General Particle Tracer, we studied the statistical temporal distributions of single-electron packets as a function of various fs pulsed-laser parameters and electron-gun configurations and fields for the exact architecture and dimensions of a Thermo Fisher Tecnai Femto ultrafast electron microscope. We focused on easily-adjustable parameters, such as laser pulse duration, laser spot size, photon energy, Wehnelt aperture diameter, and photocathode size. In addition to establishing trends and dispersion behaviors, we identify regimes within which packet duration can be 100s of fs and approach the 300 fs laser limit employed here. Overall, the results provide a detailed picture of the temporal behavior of single-electron packets in the Tecnai Femto gun region, forming the initial contribution of a larger effort.
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Affiliation(s)
- Wyatt A Curtis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN, 55455, USA.
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN, 55455, USA.
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32
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Bie YQ, Zong A, Wang X, Jarillo-Herrero P, Gedik N. A versatile sample fabrication method for ultrafast electron diffraction. Ultramicroscopy 2021; 230:113389. [PMID: 34530284 DOI: 10.1016/j.ultramic.2021.113389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/21/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022]
Abstract
Integral to the exploration of nonequilibrium phenomena in solid-state systems is the study of lattice motion after photoexcitation by a femtosecond laser pulse. For the past two decades, ultrafast electron diffraction (UED) has played a critical role in this regard. Despite remarkable progress in instrumental development, this technique is still bottlenecked by a demanding sample preparation process, where ultrathin single crystals of large lateral size are typically required. In this work, we describe an efficient, versatile method that yields high-quality, laterally extended (≥ 100 µm), and thin (≤ 50 nm) single crystals on amorphous films of Si3N4 windows. It applies to most exfoliable materials, including those reactive in ambient conditions, and promises clean, flat surfaces. Besides the natural extension to fabricating van der Waals heterostructures, our method can also be applied to future-generation UED that enables additional control of sample parameters, such as electrostatic gating and excitation by a locally enhanced terahertz field. Our work significantly expands the type of samples for UED studies and also finds application in other time-resolved techniques such as attosecond extreme-ultraviolet absorption spectroscopy. This method hence provides further opportunities to explore photoinduced transitions and to discover novel states of matter out of equilibrium.
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Affiliation(s)
- Ya-Qing Bie
- State Key Lab of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China; Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Alfred Zong
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States; University of California at Berkeley, Department of Chemistry, Berkeley, CA 94720, United States
| | - Xirui Wang
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Pablo Jarillo-Herrero
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States
| | - Nuh Gedik
- Massachusetts Institute of Technology, Department of Physics, Cambridge, MA 02139, United States.
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33
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Zhang Y, Flannigan DJ. Imaging Nanometer Phonon Softening at Crystal Surface Steps with 4D Ultrafast Electron Microscopy. NANO LETTERS 2021; 21:7332-7338. [PMID: 34406014 DOI: 10.1021/acs.nanolett.1c02524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Step edges are an important and prevalent topological feature that influence catalytic, electronic, vibrational, and structural properties arising from modulation of atomic-scale force fields due to edge-atom relaxation. Direct probing of ultrafast atomic-to-nanoscale lattice dynamics at individual steps poses a particularly significant challenge owing to demanding spatiotemporal resolution requirements. Here, we achieve such resolutions with femtosecond 4D ultrafast electron microscopy and directly image nanometer-variant softening of photoexcited phonons at individual surface steps. We find large degrees of softening precisely at the step position, with a thickness-dependent, strain-induced frequency modulation extending tens of nanometers laterally from the atomic-scale discontinuity. The effect originates from anisotropic bond dilation and photoinduced incoherent atomic displacements delineated by abrupt molecular-layer cessation. The magnitude and spatiotemporal extent of softening is quantitatively described with a finite-element transient-deformation model. The high spatiotemporal resolutions demonstrated here enable uncovering of new insights into atomic-scale structure-function relationships of highly defect-sensitive, functional materials.
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Affiliation(s)
- Yichao Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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34
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Reisbick SA, Zhang Y, Chen J, Engen PE, Flannigan DJ. Coherent Phonon Disruption and Lock-In during a Photoinduced Charge-Density-Wave Phase Transition. J Phys Chem Lett 2021; 12:6439-6447. [PMID: 34236194 DOI: 10.1021/acs.jpclett.1c01673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ultrafast manipulation of phase domains in quantum materials is a promising approach to unraveling and harnessing interwoven charge and lattice degrees of freedom. Here we find evidence for coupling of displacively excited coherent acoustic phonons (CAPs) and periodic lattice distortions (PLDs) in the intensely studied charge-density-wave material, 1T-TaS2, using 4D ultrafast electron microscopy (UEM). Initial photoinduced Bragg-peak dynamics reveal partial CAP coherence and localized c-axis dilations. Weak, partially coherent dynamics give way to higher-amplitude, increasingly coherent oscillations, the transition period of which matches that of photoinduced incommensurate domain growth and stabilization from the nearly-commensurate phase. With UEM imaging, it is found that phonon wave trains emerge from linear defects 100 ps after photoexcitation. The CAPs consist of coupled longitudinal and transverse character and propagate at anomalously high velocities along wave vectors independent from PLDs, instead being dictated by defect orientation. Such behaviors illustrate a means to control phases in quantum materials using defect-engineered coherent-phonon seeding.
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Affiliation(s)
- Spencer A Reisbick
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Yichao Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Jialiang Chen
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Paige E Engen
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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35
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Kurman Y, Dahan R, Sheinfux HH, Wang K, Yannai M, Adiv Y, Reinhardt O, Tizei LHG, Woo SY, Li J, Edgar JH, Kociak M, Koppens FHL, Kaminer I. Spatiotemporal imaging of 2D polariton wave packet dynamics using free electrons. Science 2021; 372:1181-1186. [PMID: 34112689 DOI: 10.1126/science.abg9015] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/04/2021] [Indexed: 12/19/2022]
Abstract
Coherent optical excitations in two-dimensional (2D) materials, 2D polaritons, can generate a plethora of optical phenomena that arise from the extraordinary dispersion relations that do not exist in regular materials. Probing of the dynamical phenomena of 2D polaritons requires simultaneous spatial and temporal imaging capabilities and could reveal unknown coherent optical phenomena in 2D materials. Here, we present a spatiotemporal measurement of 2D wave packet dynamics, from its formation to its decay, using an ultrafast transmission electron microscope driven by femtosecond midinfrared pulses. The ability to coherently excite phonon-polariton wave packets and probe their evolution in a nondestructive manner reveals intriguing dispersion-dependent dynamics that includes splitting of multibranch wave packets and, unexpectedly, wave packet deceleration and acceleration. Having access to the full spatiotemporal dynamics of 2D wave packets can be used to illuminate puzzles in topological polaritons and discover exotic nonlinear optical phenomena in 2D materials.
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Affiliation(s)
- Yaniv Kurman
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Raphael Dahan
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Hanan Herzig Sheinfux
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain
| | - Kangpeng Wang
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Michael Yannai
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Yuval Adiv
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Ori Reinhardt
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Luiz H G Tizei
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Steffi Y Woo
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Jiahan Li
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - James H Edgar
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - Mathieu Kociak
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Frank H L Koppens
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain. .,ICREA-Institució Catalana de Recerca i Estudis Avanats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Ido Kaminer
- Department of Electrical and Computer Engineering, Technion-Israel Institute of Technology, 32000 Haifa, Israel.
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36
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Nakamura A, Shimojima T, Ishizaka K. Finite-element simulation of photoinduced strain dynamics in silicon thin plates. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2021; 8:024103. [PMID: 33907699 PMCID: PMC8051961 DOI: 10.1063/4.0000059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/29/2021] [Indexed: 11/14/2022]
Abstract
In this paper, we investigate the femtosecond-optical-pulse-induced strain dynamics in relatively thin (100 nm) and thick (10 000 nm) silicon plates based on finite-element simulations. In the thin sample, almost spatially homogeneous excitation by the optical pulse predominantly generates a standing wave of the lowest-order acoustic resonance mode along the out-of-plane direction. At the same time, laterally propagating plate waves are emitted at the sample edge through the open edge deformation. Fourier transformation analysis reveals that the plate waves in the thin sample are mainly composed of two symmetric Lamb waves, reflecting the spatially uniform photoexcitation. In the thick sample, on the other hand, only the near surface region is photo-excited and thus a strain pulse that propagates along the out-of-plane direction is generated, accompanying the laterally propagating pulse-like strain dynamics through the edge deformation. These lateral strain pulses consist of multiple Lamb waves, including asymmetric and higher-order symmetric modes. Our simulations quantitatively demonstrate the out-of-plane and in-plane photoinduced strain dynamics in realistic silicon plates, ranging from the plate wave form to pulse trains, depending on material parameters such as sample thickness, optical penetration depth, and sound velocity.
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Affiliation(s)
- A. Nakamura
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - T. Shimojima
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
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37
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Vialla F, Del Fatti N. Time-Domain Investigations of Coherent Phonons in van der Waals Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2543. [PMID: 33348750 PMCID: PMC7766349 DOI: 10.3390/nano10122543] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 01/31/2023]
Abstract
Coherent phonons can be launched in materials upon localized pulsed optical excitation, and be subsequently followed in time-domain, with a sub-picosecond resolution, using a time-delayed pulsed probe. This technique yields characterization of mechanical, optical, and electronic properties at the nanoscale, and is taken advantage of for investigations in material science, physics, chemistry, and biology. Here we review the use of this experimental method applied to the emerging field of homo- and heterostructures of van der Waals materials. Their unique structure corresponding to non-covalently stacked atomically thin layers allows for the study of original structural configurations, down to one-atom-thin films free of interface defect. The generation and relaxation of coherent optical phonons, as well as propagative and resonant breathing acoustic phonons, are comprehensively discussed. This approach opens new avenues for the in situ characterization of these novel materials, the observation and modulation of exotic phenomena, and advances in the field of acoustics microscopy.
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Affiliation(s)
- Fabien Vialla
- Institut Lumière Matière UMR 5306, Université Claude Bernard Lyon 1, CNRS, Université de Lyon, F-69622 Villeurbanne, France;
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38
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VandenBussche EJ, Flannigan DJ. High-resolution analogue of time-domain phonon spectroscopy in the transmission electron microscope. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190598. [PMID: 33100160 PMCID: PMC7661281 DOI: 10.1098/rsta.2019.0598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
Femtosecond photoexcitation of semiconducting materials leads to the generation of coherent acoustic phonons (CAPs), the behaviours of which are linked to intrinsic and engineered electronic, optical and structural properties. While often studied with pump-probe spectroscopic techniques, the influence of nanoscale structure and morphology on CAP dynamics can be challenging to resolve with these all-optical methods. Here, we used ultrafast electron microscopy (UEM) to resolve variations in CAP dynamics caused by differences in the degree of crystallinity in as-prepared and annealed GaAs lamellae. Following in situ femtosecond photoexcitation, we directly imaged the generation and propagation dynamics of hypersonic CAPs in a mostly amorphous and, following an in situ photothermal anneal, a mostly crystalline lamella. Subtle differences in both the initial hypersonic velocities and the asymptotic relaxation behaviours were resolved via construction of space-time contour plots from phonon wavefronts. Comparison to bulk sound velocities in crystalline and amorphous GaAs reveals the influence of the mixed amorphous-crystalline morphology on CAP dispersion behaviours. Further, an increase in the asymptotic velocity following annealing establishes the sensitivity of quantitative UEM imaging to both structural and compositional variations through differences in bonding and elasticity. Implications of extending the methods and results reported here to elucidating correlated electronic, optical and structural behaviours in semiconducting materials are discussed. This article is part of a discussion meeting issue 'Dynamic in situ microscopy relating structure and function'.
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39
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Kim YJ, Lee Y, Kim K, Kwon OH. Light-Induced Anisotropic Morphological Dynamics of Black Phosphorus Membranes Visualized by Dark-Field Ultrafast Electron Microscopy. ACS NANO 2020; 14:11383-11393. [PMID: 32790334 DOI: 10.1021/acsnano.0c03644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Black phosphorus (BP) is an elemental layered material with a strong in-plane anisotropic structure. This structure is accompanied by anisotropic optical, electrical, thermal, and mechanical properties. Despite interest in BP from both fundamental and technical aspects, investigation into the structural dynamics of BP caused by strain fields, which are prevalent for two-dimensional (2D) materials and tune the material physical properties, has been overlooked. Here, we report the morphological dynamics of photoexcited BP membranes observed using time-resolved diffractograms and dark-field images obtained via ultrafast electron microscopy. Aided by 4D reconstruction, we visualize the nonequilibrium bulging of thin BP membranes and reveal that the buckling transition is driven by impulsive thermal stress upon photoexcitation in real time. The bulging, buckling, and flattening (on strain release) showed anisotropic spatiotemporal behavior. Our observations offer insights into the fleeting morphology of anisotropic 2D matter and provide a glimpse into the mapping of transient, modulated physical properties upon impulsive excitation, as well as strain engineering at the nanoscale.
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Affiliation(s)
- Ye-Jin Kim
- Department of Chemistry, School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), 50 UNIST-gil, Ulsan 44919, Korea
| | - Yangjin Lee
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), 50 Yonsei-ro, Seoul 03722, Korea
| | - Kwanpyo Kim
- Department of Physics, Yonsei University, 50 Yonsei-ro, Seoul 03722, Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), 50 Yonsei-ro, Seoul 03722, Korea
| | - Oh-Hoon Kwon
- Department of Chemistry, School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), 50 UNIST-gil, Ulsan 44919, Korea
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40
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Nakamura A, Shimojima T, Chiashi Y, Kamitani M, Sakai H, Ishiwata S, Li H, Ishizaka K. Nanoscale Imaging of Unusual Photoacoustic Waves in Thin Flake VTe 2. NANO LETTERS 2020; 20:4932-4938. [PMID: 32463678 DOI: 10.1021/acs.nanolett.0c01006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The control of acoustic phonons, which are the carriers of sound and heat, has become the focus of increasing attention because of a demand for manipulating the sonic and thermal properties of nanometric devices. In particular, the photoacoustic effect using ultrafast optical pulses has a promising potential for the optical manipulation of phonons in the picosecond time regime. So far, its mechanism has been mostly based on the commonplace thermoelastic expansion in isotropic media, which has limited applicability. In this study, we investigate a conceptually new mechanism of the photoacoustic effect involving a structural instability that utilizes a transition-metal dichalcogenide VTe2 with a ribbon-type charge-density-wave (CDW). Ultrafast electron microscope imaging and diffraction measurements reveal the generation and propagation of unusual acoustic waves in a nanometric thin plate associated with optically induced instantaneous CDW dissolution. Our results highlight the capability of photoinduced structural instabilities as a source of coherent acoustic waves.
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Affiliation(s)
- Asuka Nakamura
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | | | - Yusuke Chiashi
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
| | - Manabu Kamitani
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Hideaki Sakai
- Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Shintaro Ishiwata
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
- Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Han Li
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
| | - Kyoko Ishizaka
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
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41
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Zandi O, Sykes AE, Cornelius RD, Alcorn FM, Zerbe BS, Duxbury PM, Reed BW, van der Veen RM. Transient lensing from a photoemitted electron gas imaged by ultrafast electron microscopy. Nat Commun 2020; 11:3001. [PMID: 32532996 PMCID: PMC7293293 DOI: 10.1038/s41467-020-16746-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 05/18/2020] [Indexed: 11/28/2022] Open
Abstract
Understanding and controlling ultrafast charge carrier dynamics is of fundamental importance in diverse fields of (quantum) science and technology. Here, we create a three-dimensional hot electron gas through two-photon photoemission from a copper surface in vacuum. We employ an ultrafast electron microscope to record movies of the subsequent electron dynamics on the picosecond-nanosecond time scale. After a prompt Coulomb explosion, the subsequent dynamics is characterized by a rapid oblate-to-prolate shape transformation of the electron gas, and periodic and long-lived electron cyclotron oscillations inside the magnetic field of the objective lens. In this regime, the collective behavior of the oscillating electrons causes a transient, mean-field lensing effect and pronounced distortions in the images. We derive an analytical expression for the time-dependent focal length of the electron-gas lens, and perform numerical electron dynamics and probe image simulations to determine the role of Coulomb self-fields and image charges. This work inspires the visualization of cyclotron dynamics inside two-dimensional electron-gas materials and enables the elucidation of electron/plasma dynamics and properties that could benefit the development of high-brightness electron and X-ray sources.
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Affiliation(s)
- Omid Zandi
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Allan E Sykes
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ryan D Cornelius
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Francis M Alcorn
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Brandon S Zerbe
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Phillip M Duxbury
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Bryan W Reed
- Integrated Dynamic Electron Solutions, Inc. (IDES), Pleasanton, CA, 94588, USA
| | - Renske M van der Veen
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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Abstract
Time-resolved electron microscopy is based on the excitation of a sample by pulsed laser radiation and its probing by synchronized photoelectron bunches in the electron microscope column. With femtosecond lasers, if probing pulses with a small number of electrons—in the limit, single-electron wave packets—are used, the stroboscopic regime enables ultrahigh spatiotemporal resolution to be obtained, which is not restricted by the Coulomb repulsion of electrons. This review article presents the current state of the ultrafast electron microscopy (UEM) method for detecting the structural dynamics of matter in the time range from picoseconds to attoseconds. Moreover, in the imaging mode, the spatial resolution lies, at best, in the subnanometer range, which limits the range of observation of structural changes in the sample. The ultrafast electron diffraction (UED), which created the methodological basis for the development of UEM, has opened the possibility of creating molecular movies that show the behavior of the investigated quantum system in the space-time continuum with details of sub-Å spatial resolution. Therefore, this review on the development of UEM begins with a description of the main achievements of UED, which formed the basis for the creation and further development of the UEM method. A number of recent experiments are presented to illustrate the potential of the UEM method.
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Chen Q, Dwyer C, Sheng G, Zhu C, Li X, Zheng C, Zhu Y. Imaging Beam-Sensitive Materials by Electron Microscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907619. [PMID: 32108394 DOI: 10.1002/adma.201907619] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/20/2019] [Indexed: 05/15/2023]
Abstract
Electron microscopy allows the extraction of multidimensional spatiotemporally correlated structural information of diverse materials down to atomic resolution, which is essential for figuring out their structure-property relationships. Unfortunately, the high-energy electrons that carry this important information can cause damage by modulating the structures of the materials. This has become a significant problem concerning the recent boost in materials science applications of a wide range of beam-sensitive materials, including metal-organic frameworks, covalent-organic frameworks, organic-inorganic hybrid materials, 2D materials, and zeolites. To this end, developing electron microscopy techniques that minimize the electron beam damage for the extraction of intrinsic structural information turns out to be a compelling but challenging need. This article provides a comprehensive review on the revolutionary strategies toward the electron microscopic imaging of beam-sensitive materials and associated materials science discoveries, based on the principles of electron-matter interaction and mechanisms of electron beam damage. Finally, perspectives and future trends in this field are put forward.
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Affiliation(s)
- Qiaoli Chen
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Christian Dwyer
- Department of Physics, Arizona State University, Tempe, AZ, 85287-1504, USA
| | - Guan Sheng
- Advanced Membranes and Porous Materials Center, Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Chongzhi Zhu
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Xiaonian Li
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Changlin Zheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
| | - Yihan Zhu
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
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44
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Du DX, Flannigan DJ. Imaging phonon dynamics with ultrafast electron microscopy: Kinematical and dynamical simulations. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:024103. [PMID: 32341940 PMCID: PMC7166119 DOI: 10.1063/1.5144682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
Ultrafast x-ray and electron scattering techniques have proven to be useful for probing the transient elastic lattice deformations associated with photoexcited coherent acoustic phonons. Indeed, femtosecond electron imaging using an ultrafast electron microscope (UEM) has been used to directly image the influence of nanoscale structural and morphological discontinuities on the emergence, propagation, dispersion, and decay behaviors in a variety of materials. Here, we describe our progress toward the development of methods ultimately aimed at quantifying acoustic-phonon properties from real-space UEM images via conventional image simulation methods extended to the associated strain-wave lattice deformation symmetries and extents. Using a model system consisting of pristine single-crystal Ge and a single, symmetric Lamb-type guided-wave mode, we calculate the transient strain profiles excited in a wedge specimen and then apply both kinematical- and dynamical-scattering methods to simulate the resulting UEM bright-field images. While measurable contrast strengths arising from the phonon wavetrains are found for optimally oriented specimens using both approaches, incorporation of dynamical scattering effects via a multi-slice method returns better qualitative agreement with experimental observations. Contrast strengths arising solely from phonon-induced local lattice deformations are increased by nearly an order of magnitude when incorporating multiple electron scattering effects. We also explicitly demonstrate the effects of changes in global specimen orientation on the observed contrast strength, and we discuss the implications for increasing the sophistication of the model with respect to quantification of phonon properties from UEM images.
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Affiliation(s)
| | - David J. Flannigan
- Author to whom correspondence should be addressed:. Tel.: +1 612-625-3867
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45
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Reisbick SA, Zhang Y, Flannigan DJ. Influence of Discrete Defects on Observed Acoustic-Phonon Dynamics in Layered Materials Probed with Ultrafast Electron Microscopy. J Phys Chem A 2020; 124:1877-1884. [PMID: 32068411 DOI: 10.1021/acs.jpca.9b12026] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The structural anisotropy of layered materials leads to disparate lattice responses along different crystallographic directions following femtosecond photoexcitation. Ultrafast scattering methods are well-suited to resolving such responses, though probe size and specimen structure and morphology must be considered when interpreting results. Here we use ultrafast electron microscopy (UEM) imaging and diffraction to study the influence of individual multilayer terraces and few-layer step-edges on acoustic-phonon dynamics in 1T-TaS2 and 2H-MoS2. In TaS2, we find that a multilayer terrace produces distinct, localized responses arising from thickness-dependent c-axis phonon dynamics. Convolution of the responses is demonstrated with ultrafast selected-area diffraction by limiting the probe size and training it on the region of interest. This results in a reciprocal-space frequency response that is a convolution of the spatially separated behaviors. Sensitivity of phonon dynamics to few-layer step-edges in MoS2 and the capability of UEM imaging to resolve the influence of such defects are also demonstrated. Spatial frequency maps from the UEM image series reveal regions separated by a four-layer step-edge having 60.0 GHz and 63.3 GHz oscillation frequencies, again linked to c-axis phonon propagation. As with ultrafast diffraction, signal convolution is demonstrated by continuous increase of the size of the selected region of interest used in the analysis.
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Affiliation(s)
- Spencer A Reisbick
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Yichao Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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46
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Zhang Y, Flannigan DJ. Observation of Anisotropic Strain-Wave Dynamics and Few-Layer Dephasing in MoS 2 with Ultrafast Electron Microscopy. NANO LETTERS 2019; 19:8216-8224. [PMID: 31658814 DOI: 10.1021/acs.nanolett.9b03596] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The large elastic strains that can be sustained by transition metal dichalcogenides (TMDs), and the sensitivity of electronic properties to that strain, make these materials attractive targets for tunable optoelectronic devices. Defects have also been shown to influence the optical and electronic properties, characteristics that are especially important to understand for applications requiring high precision and sensitivity. Importantly, photoexcitation of TMDs is known to generate transient strain effects but the associated intralayer and interlayer low-frequency (tens of GHz) acoustic-phonon modes are largely unexplored, especially in relation to defects common to such materials. Here, with femtosecond electron imaging in an ultrafast electron microscope (UEM), we directly observe distinct photoexcited strain-wave dynamics specific to both the ab basal planes and the principal c-axis crystallographic stacking direction in multilayer 2H-MoS2, and we elucidate the microscopic interconnectedness of these modes to one another and to discrete defects, such as few-layer crystal step edges. By probing 3D structural information within a nanometer-picosecond 2D projected UEM image series, we were able to observe the excitation and evolution of both modes simultaneously. In this way, we found evidence of a delay between mode excitations; initiation of the interlayer (c-axis) strain-wave mode precedes the intralayer (ab plane) mode by 2.4 ps. Further, the intralayer mode is preferentially excited at free basal-plane edges, thus suggesting the initial impulsive structural changes along the c-axis direction and the increased freedom of motion of the MoS2 layer edges at terraces and step edges combine to launch in-plane strain waves at the longitudinal speed of sound (here observed to be 7.8 nm/ps). Sensitivity of the c-axis mode to layer number is observed through direct imaging of a picosecond spatiotemporal dephasing of the lattice oscillation in discrete crystal regions separated by a step edge consisting of four MoS2 layers. These results uncover new insights into the fundamental nanoscale structural responses of layered materials to ultrafast photoexcitation and illustrate the influence defects common to these materials have on behaviors that may impact the emergent optoelectronic properties.
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Affiliation(s)
- Yichao Zhang
- Department of Chemical Engineering and Materials Science , University of Minnesota , 421 Washington Avenue SE , Minneapolis , Minnesota 55455 , United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science , University of Minnesota , 421 Washington Avenue SE , Minneapolis , Minnesota 55455 , United States
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47
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Verhoeven W, van Rens JFM, Kemper AH, Rietman EH, van Doorn HA, Koole I, Kieft ER, Mutsaers PHA, Luiten OJ. Design and characterization of dielectric filled TM 110 microwave cavities for ultrafast electron microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:083703. [PMID: 31472630 DOI: 10.1063/1.5080003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 08/04/2019] [Indexed: 06/10/2023]
Abstract
Microwave cavities oscillating in the TM110 mode can be used as dynamic electron-optical elements inside an electron microscope. By filling the cavity with a dielectric material, it becomes more compact and power efficient, facilitating the implementation in an electron microscope. However, the incorporation of the dielectric material makes the manufacturing process more difficult. Presented here are the steps taken to characterize the dielectric material and to reproducibly fabricate dielectric filled cavities. Also presented are two versions with improved capabilities. The first, called a dual-mode cavity, is designed to support two modes simultaneously. The second has been optimized for low power consumption. With this optimized cavity, a magnetic field strength of 2.84 ± 0.07 mT was generated at an input power of 14.2 ± 0.2 W. Due to the low input powers and small dimensions, these dielectric cavities are ideal as electron-optical elements for electron microscopy setups.
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Affiliation(s)
- W Verhoeven
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - J F M van Rens
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - A H Kemper
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - E H Rietman
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - H A van Doorn
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - I Koole
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - E R Kieft
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands
| | - P H A Mutsaers
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - O J Luiten
- Department of Applied Physics, Coherence and Quantum Technology Group, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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48
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Bach N, Domröse T, Feist A, Rittmann T, Strauch S, Ropers C, Schäfer S. Coulomb interactions in high-coherence femtosecond electron pulses from tip emitters. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:014301. [PMID: 30868085 PMCID: PMC6404915 DOI: 10.1063/1.5066093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/08/2019] [Indexed: 05/26/2023]
Abstract
Tip-based photoemission electron sources offer unique properties for ultrafast imaging, diffraction, and spectroscopy experiments with highly coherent few-electron pulses. Extending this approach to increased bunch-charges requires a comprehensive experimental study on Coulomb interactions in nanoscale electron pulses and their impact on beam quality. For a laser-driven Schottky field emitter, we assess the transverse and longitudinal electron pulse properties in an ultrafast transmission electron microscope at a high photoemission current density. A quantitative characterization of electron beam emittance, pulse duration, spectral bandwidth, and chirp is performed. Due to the cathode geometry, Coulomb interactions in the pulse predominantly occur in the direct vicinity to the tip apex, resulting in a well-defined pulse chirp and limited emittance growth. Strategies for optimizing electron source parameters are identified, enabling advanced ultrafast transmission electron microscopy approaches, such as phase-resolved imaging and holography.
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Affiliation(s)
- Nora Bach
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Till Domröse
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Armin Feist
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Thomas Rittmann
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Stefanie Strauch
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Claus Ropers
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
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49
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Beane G, Devkota T, Brown BS, Hartland GV. Ultrafast measurements of the dynamics of single nanostructures: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:016401. [PMID: 30485256 DOI: 10.1088/1361-6633/aaea4b] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The ability to study single particles has revolutionized nanoscience. The advantage of single particle spectroscopy measurements compared to conventional ensemble studies is that they remove averaging effects from the different sizes and shapes that are present in the samples. In time-resolved experiments this is important for unraveling homogeneous and inhomogeneous broadening effects in lifetime measurements. In this report, recent progress in the development of ultrafast time-resolved spectroscopic techniques for interrogating single nanostructures will be discussed. The techniques include far-field experiments that utilize high numerical aperture (NA) microscope objectives, near-field scanning optical microscopy (NSOM) measurements, ultrafast electron microscopy (UEM), and time-resolved x-ray diffraction experiments. Examples will be given of the application of these techniques to studying energy relaxation processes in nanoparticles, and the motion of plasmons, excitons and/or charge carriers in different types of nanostructures.
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Affiliation(s)
- Gary Beane
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States of America
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50
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VandenBussche EJ, Flannigan DJ. Sources of error in Debye-Waller-effect measurements relevant to studies of photoinduced structural dynamics. Ultramicroscopy 2018; 196:111-120. [PMID: 30352384 DOI: 10.1016/j.ultramic.2018.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 09/23/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
We identify and quantify several practical effects likely to be present in both static and ultrafast electron-scattering experiments that may interfere with the Debye-Waller (DW) effect. Using 120-nm thick, small-grained, polycrystalline aluminum foils as a test system, we illustrate the impact of specimen tilting, in-plane translation, and changes in z height on Debye-Scherrer-ring intensities. We find that tilting by less than one degree can result in statistically-significant changes in diffracted-beam intensities for large specimen regions containing > 105 nanocrystalline grains. We demonstrate that, in addition to effective changes in the field of view with tilting, slight texturing of the film can result in deviations from expected DW-effect behavior. Further, we find that in-plane translations of as little as 20 nm also produce statistically-significant intensity changes, while normalization to total image counts eliminates such effects arising from changes in z height. The results indicate that the use of polycrystalline films in ultrafast electron-scattering experiments can greatly reduce the negative impacts of these effects as compared to single-crystal specimens, though it does not entirely eliminate them. Thus, it is important to account for such effects when studying thin-foil specimens having relatively short reciprocal-lattice rods.
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Affiliation(s)
- Elisah J VandenBussche
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, MN 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, MN 55455, United States.
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