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Kempers ST, Borrelli S, Kieft ER, van Doorn HA, Mutsaers PHA, Luiten OJ. Photodiode-based time zero determination for ultrafast electron microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:064301. [PMID: 37941992 PMCID: PMC10629968 DOI: 10.1063/4.0000218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/17/2023] [Indexed: 11/10/2023]
Abstract
Pump-probe experiments in ultrafast electron microscopy require temporal overlap between the pump and probe pulses. Accurate measurements of the time delay between them allows for the determination of the time zero, the moment in time where both pulses perfectly overlap. In this work, we present the use of a photodiode-based alignment method for these time zero measurements. The cheap and easy-to-use device consists of a photodiode in a sample holder and enables us to temporally align individual, single-electron pulses with femtosecond laser pulses. In a first device, a temporal resolution of 24 ps is obtained, limited by the photodiode design. Future work will utilize a smaller photodiode with a lower capacitance, which will increase the temporal resolution and add spatial resolution as well. This upgrade will bring the method toward the micrometer and picosecond spatiotemporal resolution.
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Affiliation(s)
- S. T. Kempers
- Eindhoven University of Technology, Coherence and Quantum Technology, 5600 MB Eindhoven, the Netherlands
| | - S. Borrelli
- Eindhoven University of Technology, Coherence and Quantum Technology, 5600 MB Eindhoven, the Netherlands
| | - E. R. Kieft
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GC Eindhoven, The Netherlands
| | - H. A. van Doorn
- Eindhoven University of Technology, Coherence and Quantum Technology, 5600 MB Eindhoven, the Netherlands
| | - P. H. A. Mutsaers
- Eindhoven University of Technology, Coherence and Quantum Technology, 5600 MB Eindhoven, the Netherlands
| | - O. J. Luiten
- Eindhoven University of Technology, Coherence and Quantum Technology, 5600 MB Eindhoven, the Netherlands
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2
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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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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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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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5
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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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Chao HW, Huang RJ, Li YC, Chang TH. W-band circular TM 11 mode converter for gyrotrons. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053540. [PMID: 34243346 DOI: 10.1063/5.0046216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/03/2021] [Indexed: 06/13/2023]
Abstract
This work proposes a methodology to convert a rectangular TE10 mode to a circular TM11 mode using an H-plane power divider at W-band. The divider evenly splits the input signal into two parts with the same amplitude and phase. One of the waves then goes through a wider rectangular waveguide with a lower cutoff frequency. After propagating through a specific length, the two waves differ by 180°. The two out-of-phase waves can jointly synthesize the circular TM11 mode with high mode purity. This power divider is structurally simple and capable of high-power operation. The full-wave simulation shows that the metal's conductivity affects the transmission of two-mode converters joined back-to-back. The measured back-to-back transmission agrees with the simulation result except for minor quantitative differences. The measured 3-dB bandwidth is 2.8 GHz with a center frequency of 93.6 GHz, which warrants the success of the TM11 mode gyrotrons.
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Affiliation(s)
- Hsien-Wen Chao
- Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Ren-Jun Huang
- Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yi-Chin Li
- Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Tsun-Hsu Chang
- Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan
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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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Wu H, Friedrich H, Patterson JP, Sommerdijk NAJM, de Jonge N. Liquid-Phase Electron Microscopy for Soft Matter Science and Biology. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2001582. [PMID: 32419161 DOI: 10.1002/adma.202001582] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/05/2020] [Accepted: 04/06/2020] [Indexed: 05/20/2023]
Abstract
Innovations in liquid-phase electron microscopy (LP-EM) have made it possible to perform experiments at the optimized conditions needed to examine soft matter. The main obstacle is conducting experiments in such a way that electron beam radiation can be used to obtain answers for scientific questions without changing the structure and (bio)chemical processes in the sample due to the influence of the radiation. By overcoming these experimental difficulties at least partially, LP-EM has evolved into a new microscopy method with nanometer spatial resolution and sub-second temporal resolution for analysis of soft matter in materials science and biology. Both experimental design and applications of LP-EM for soft matter materials science and biological research are reviewed, and a perspective of possible future directions is given.
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Affiliation(s)
- Hanglong Wu
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, 5600 MB, The Netherlands
| | - Heiner Friedrich
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, 5600 MB, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, 5600 MB, The Netherlands
| | - Joseph P Patterson
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Nico A J M Sommerdijk
- Department of Biochemistry, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands
| | - Niels de Jonge
- INM - Leibniz Institute for New Materials, Saarbrücken, 66123, Germany
- Department of Physics, Saarland University, Saarbrücken, 66123, Germany
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Investigation of the Thermal Properties of Electrodes on the Film and Its Heating Behavior Induced by Microwave Irradiation in Mounting Processes. Processes (Basel) 2020. [DOI: 10.3390/pr8050557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have developed a novel microwave (MW) soldering system using a cylindrical single-mode TM110 MW cavity that spatially separates the electric fields at the top and bottom of the cavity and the magnetic field at the center of the cavity. This MW reactor system automatically detects the suitable resonance frequency and provides the optimum MW irradiation conditions in the cylindrical cavity via a power feedback loop. Furthermore, we investigated the temperature properties of electrodes by MW heating with the simulation of a magnetic field in the TM110 cavity toward the mounting of electronic components by MW heating. We also developed a short-time melting technology for solder paste on polyimide substrate using MW heating and succeeded in mounting a temperature sensor using the novel MW heating system without damaging the electronic components, electronic circuits, and the substrate.
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