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Hui D, Alqattan H, Sennary M, Golubev NV, Hassan MT. Attosecond electron microscopy and diffraction. SCIENCE ADVANCES 2024; 10:eadp5805. [PMID: 39167650 PMCID: PMC11338230 DOI: 10.1126/sciadv.adp5805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 07/19/2024] [Indexed: 08/23/2024]
Abstract
Advances in attosecond spectroscopy have enabled tracing and controlling the electron motion dynamics in matter, although they have yielded insufficient information about the electron dynamic in the space domain. Hence, ultrafast electron and x-ray imaging tools have been developed to image the ultrafast dynamics of matter in real time and space. The cutting-edge temporal resolution of these imaging tools is on the order of a few tens to a hundred femtoseconds, limiting imaging to the atomic dynamics and leaving electron motion imaging out of reach. Here, we obtained the attosecond temporal resolution in the transmission electron microscope, which we coined "attomicroscopy." We demonstrated this resolution by the attosecond diffraction measurements of the field-driven electron dynamics in graphene. This attosecond imaging tool would provide more insights into electron motion and directly connect it to the structural dynamics of matter in real-time and space domains, opening the door for long-anticipated real-life attosecond science applications in quantum physics, chemistry, and biology.
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Affiliation(s)
| | | | - Mohamed Sennary
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
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2
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de Raadt TCH, Franssen JGH, Luiten OJ. Subpicosecond Ultracold Electron Source. PHYSICAL REVIEW LETTERS 2023; 130:205001. [PMID: 37267545 DOI: 10.1103/physrevlett.130.205001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 03/01/2023] [Accepted: 03/29/2023] [Indexed: 06/04/2023]
Abstract
We present the first observation of subpicosecond electron bunches from an ultracold electron source. This source is based on near-threshold, two-step, femtosecond photoionization of laser-cooled rubidium gas in a grating magneto-optical trap. Bunch lengths as short as 735±7 fs (rms) have been measured in the self-compression point of the source by means of ponderomotive scattering of the electrons by a 25 fs, 800 nm laser pulse. The observed temporal structure of the electron bunch depends on the central wavelength of the ionization laser pulse, in agreement with detailed simulations of the atomic photoionization process. This shows that the bunch length limit imposed by the atomic photoionization process has been reached.
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Affiliation(s)
- T C H de Raadt
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - J G H Franssen
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - O J Luiten
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
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3
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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: 13] [Impact Index Per Article: 13.0] [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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4
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Garming MWH, Kruit P, Hoogenboom JP. Imaging resonant micro-cantilever movement with ultrafast scanning electron microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093702. [PMID: 36182522 DOI: 10.1063/5.0089086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 08/11/2022] [Indexed: 06/16/2023]
Abstract
Here, we demonstrate ultrafast scanning electron microscopy (SEM) for making ultrafast movies of mechanical oscillators at resonance with nanoscale spatiotemporal resolution. Locking the laser excitation pulse sequence to the electron probe pulses allows for video framerates over 50 MHz, well above the detector bandwidth, while maintaining the electron beam resolution and depth of focus. The pulsed laser excitation is tuned to the oscillator resonance with a pulse frequency modulation scheme. We use an atomic force microscope cantilever as a model resonator, for which we show ultrafast real-space imaging of the first and even the 2 MHz second harmonic oscillation as well as verification of power and frequency response via the ultrafast movies series. We detect oscillation amplitudes as small as 20 nm and as large as 9 μm. Our implementation of ultrafast SEM for visualizing nanoscale oscillatory dynamics adds temporal resolution to the domain of SEM, providing new avenues for the characterization and development of devices based on micro- and nanoscale resonant motion.
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Affiliation(s)
- Mathijs W H Garming
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Pieter Kruit
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Jacob P Hoogenboom
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
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5
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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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6
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MOFs-derived hierarchical porous carbon confining the monodisperse Ni and defective WOx for efficient and stable hydrogenolysis of cellulose to ethylene glycol. RESEARCH ON CHEMICAL INTERMEDIATES 2022. [DOI: 10.1007/s11164-022-04718-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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7
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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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8
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Li S, Sun J, Guan J. Strategies to improve electrocatalytic and photocatalytic performance of two-dimensional materials for hydrogen evolution reaction. CHINESE JOURNAL OF CATALYSIS 2021. [DOI: 10.1016/s1872-2067(20)63693-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Arjun A, Bolhuis PG. Molecular Understanding of Homogeneous Nucleation of CO 2 Hydrates Using Transition Path Sampling. J Phys Chem B 2021; 125:338-349. [PMID: 33379869 PMCID: PMC7816195 DOI: 10.1021/acs.jpcb.0c09915] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/11/2020] [Indexed: 11/29/2022]
Abstract
Carbon dioxide hydrate is a solid built from hydrogen-bond stabilized water cages that encapsulate individual CO2 molecules. As potential candidates for reducing greenhouse gases, hydrates have attracted attention from both the industry and scientific community. Under high pressure and low temperature, hydrates are formed spontaneously from a mixture of CO2 and water via nucleation and growth. Yet, for moderate undercooling, i.e., moderate supersaturation, studying hydrate formation with molecular simulations is very challenging due to the high nucleation barriers involved. We investigate the homogeneous nucleation mechanism of CO2 hydrate as a function of temperature using transition path sampling (TPS), which generates ensembles of unbiased dynamical trajectories across the high barrier between the liquid and solid states. The resulting path ensembles reveal that at high driving force (low temperature), amorphous structures are predominantly formed, with 4151062 cages being the most abundant. With increasing temperature, the nucleation mechanism changes, and 51262 becomes the most abundant cage type, giving rise to the crystalline sI structure. Reaction coordinate analysis can reveal the most important collective variable involved in the mechanism. With increasing temperature, we observe a shift from a single feature (size of the nucleus) to a 2-dimensional (size and cage type) variable as the salient ingredient of the reaction coordinate, and then back to only the nucleus size. This finding is in line with the underlying shift from an amorphous to a crystalline nucleation channel. Modeling such complex phase transformations using transition path sampling gives unbiased insight into the molecular mechanisms toward different polymorphs, and how these are determined by thermodynamics and kinetics. This study will be beneficial for researchers aiming to produce such hydrates with different polymorphic forms.
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Affiliation(s)
- A. Arjun
- van ’t Hoff Institute
for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
| | - P. G. Bolhuis
- van ’t Hoff Institute
for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
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10
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Fenwick KL, England DG, Bustard PJ, Fraser JM, Sussman BJ. Carving out configurable ultrafast pulses from a continuous wave source via the optical Kerr effect. OPTICS EXPRESS 2020; 28:24845-24853. [PMID: 32907016 DOI: 10.1364/oe.399878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
Wavelength-tunable, time-locked pairs of ultrafast pulses are crucial in modern-day time-resolved measurements. We demonstrate a simple means of generating configurable optical pulse sequences: sub-picosecond pulses are carved out from a continuous wave laser via pump-induced optical Kerr switching in 10 cm of a commercial single-mode fiber. By introducing dispersion to the pump, the near transform-limited switched pulse duration is tuned between 305-570 fs. Two- and four-pulse signal trains are also generated by adding birefringent α-BBO plates in the pump beam. These results highlight an ultrafast light source with intrinsic timing stability and pulse-to-pulse phase coherence, where pulse generation could be adapted to wavelengths ranging from ultraviolet to infrared.
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11
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Zhao J, Bakr OM, Mohammed OF. Ultrafast electron imaging of surface charge carrier dynamics at low voltage. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:021001. [PMID: 32266302 PMCID: PMC7105398 DOI: 10.1063/4.0000007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 03/10/2020] [Indexed: 06/11/2023]
Abstract
The performance of optoelectronic devices strongly depends on charge carrier dynamics on top of surfaces of the absorber layers. Unfortunately, this information cannot be selectively probed using conventional ultrafast laser spectroscopic methods, due to the large penetration depth (tens of nm to μm) of the photon pulses in the pump-probe configurations. Therefore, ultrafast time-resolved approaches that can directly and selectively visualize the behavior of the surface carrier dynamics are urgently needed. Here, we introduce a novel methodology of low-voltage scanning ultrafast electron microscopy that can take ultrafast time-resolved images (snapshots) of the surface of materials at the sub-nanometer level. By this approach, the surface of the photoactive materials is optically excited and imaged, using a pulsed low-voltage electron beam (1 keV) that interacts with the surface to generate secondary electrons with an energy of a few eV, and that are emitted only from the top surface of materials, providing direct information about the carrier dynamics and the localization of electron/holes in real space and time. An outlook on the potential applications of this low voltage approach in different disciplines will also be discussed.
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Affiliation(s)
- Jianfeng Zhao
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Osman M Bakr
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Omar F Mohammed
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
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12
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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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13
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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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14
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Hussain S, Haji-Akbari A. Studying rare events using forward-flux sampling: Recent breakthroughs and future outlook. J Chem Phys 2020; 152:060901. [DOI: 10.1063/1.5127780] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sarwar Hussain
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
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15
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Shaheen BS, El-Zohry AM, Zhao J, Yin J, Hedhili MN, Bakr OM, Mohammed OF. Real-Space Mapping of Surface-Oxygen Defect States in Photovoltaic Materials Using Low-Voltage Scanning Ultrafast Electron Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:7760-7767. [PMID: 31951364 DOI: 10.1021/acsami.9b20215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ultrathin layers of native oxides on the surface of photovoltaic materials may act as very efficient carrier trapping/recombination centers, thus significantly affecting their interfacial photophysical properties. How ultrathin oxide layers affect the surface and interface carrier dynamics cannot be selectively accessed by conventional ultrafast transient spectroscopic methods due to the deep penetration depth (tens to thousands of nanometers) of the pump/probe laser pulses. Herein, scanning ultrafast electron microscopy (S-UEM) at a low voltage of 1 keV electrons was recently developed at KAUST to selectively map the ultrafast charge carrier dynamics of a few layers on the top surfaces of photovoltaic materials. Unlike high-voltage 30 keV experiments, at 1 keV, the depth of detected secondary electrons (SEs) underneath the surface is significantly reduced 5 times, thus making it possible to visualize the dynamics of charge carrier from the uppermost surface of photoactive layers. More specifically, this new approach has been employed to explore and decipher the tremendous impact of native oxide layers and oxygen defect states on charge carrier dynamics in space and time simultaneously at sub-nanometer levels on several photovoltaic material surfaces, including Si, GaAs, CdTe, and CdZnTe single crystals. Interestingly, the contrast in the SEs time-resolved difference images switched from a dark "energy-loss mechanism" to a bright "energy-gain mechanism" only by removing the layers of surface oxides. Moreover, the charge carrier recombination was estimated and found to be dramatically affected by the native oxide layers. The density functional theory (DFT) calculations demonstrate that the work function of oxygen-terminated Si surface also increases slightly upon optical excitation and makes for less SE intensity, providing another piece of evidence that the origin of the dark contrast observed on these material surfaces should be assigned to the surface oxide formation, mainly oxygen defect states in the band gap and/or work function increment. Our findings provide a new method and pave the way for evaluating the effect of surface morphology and defects, including but not limited to native oxide, on charge carrier dynamics, and interfacial properties of photovoltaic absorber layers.
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Affiliation(s)
- Basamat S Shaheen
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Ahmed M El-Zohry
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Jianfeng Zhao
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Jun Yin
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Mohamed N Hedhili
- Core Labs , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Osman M Bakr
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Omar F Mohammed
- Division of Physical Science and Engineering , King Abdullah University of Science and Technology , Thuwal 23955-6900 , Kingdom of Saudi Arabia
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16
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Gao Y, Nie W, Wang X, Fan F, Li C. Advanced space- and time-resolved techniques for photocatalyst studies. Chem Commun (Camb) 2020; 56:1007-1021. [DOI: 10.1039/c9cc07128h] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nanoparticle photocatalysts present the obvious characteristic of heterogeneity in structure, energy, and function at spatial and temporal scales.
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Affiliation(s)
- Yuying Gao
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM)
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
| | - Wei Nie
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM)
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
| | - Xiuli Wang
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM)
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
| | - Fengtao Fan
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM)
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
| | - Can Li
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM)
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
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17
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Ren J, Wang Y, Yao Y, Wang Y, Fei X, Qi P, Lin S, Kaplan DL, Buehler MJ, Ling S. Biological Material Interfaces as Inspiration for Mechanical and Optical Material Designs. Chem Rev 2019; 119:12279-12336. [DOI: 10.1021/acs.chemrev.9b00416] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jing Ren
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Yu Wang
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Yuan Yao
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Yang Wang
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Xiang Fei
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, International Joint Laboratory for Advanced Fiber and Low-Dimension Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Ping Qi
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Shihui Lin
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Markus J. Buehler
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Shengjie Ling
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
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18
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Zhu C, Zheng D, Wang H, Zhang M, Li Z, Sun S, Xu P, Tian H, Li Z, Yang H, Li J. Development of analytical ultrafast transmission electron microscopy based on laser-driven Schottky field emission. Ultramicroscopy 2019; 209:112887. [PMID: 31739190 DOI: 10.1016/j.ultramic.2019.112887] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/29/2019] [Accepted: 11/09/2019] [Indexed: 10/25/2022]
Abstract
A new design scheme for ultrafast transmission electron microscopy (UTEM) has been developed based on a Schottky-type field emission gun (FEG) at the Institute of Physics, Chinese Academy of Sciences (IOP CAS). In this UTEM setup, electron pulse emission is achieved by integrating a laser port between the electron gun and the column and the resulting microscope can operate in either continuous or pulsed mode. In pulsed mode, the optimized electron beam properties are an energy width of ~0.65 eV, micrometer-scale coherence lengths and sub-picosecond pulse durations. The potential applications of this UTEM, which include electron diffraction, high-resolution imaging, electron energy loss spectroscopy, and photon-induced near-field electron microscopy, are demonstrated using ultrafast electron pulses. Furthermore, we use a nanosecond laser (~10 ns) to show that the laser-driven FEG can support high-quality TEM imaging and electron holography when using a stroboscopic configuration. Our results also indicate that FEG-based ultrafast electron sources may enable high-performance analytical UTEM.
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Affiliation(s)
- Chunhui Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Dingguo Zheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Hong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Ming Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhongwen Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shuaishuai Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Peng Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zian Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huaixin Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China; Yangtze River Delta Physics Research Center Co., Ltd., Liyang, Jiangsu, 213300, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jianqi Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China.
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19
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Zhang L, Hoogenboom JP, Cook B, Kruit P. Photoemission sources and beam blankers for ultrafast electron microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:051501. [PMID: 31592440 PMCID: PMC6764838 DOI: 10.1063/1.5117058] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/03/2019] [Indexed: 06/01/2023]
Abstract
Observing atomic motions as they occur is the dream goal of ultrafast electron microscopy (UEM). Great progress has been made so far thanks to the efforts of many scientists in developing the photoemission sources and beam blankers needed to create short pulses of electrons for the UEM experiments. While details on these setups have typically been reported, a systematic overview of methods used to obtain a pulsed beam and a comparison of relevant source parameters have not yet been conducted. In this report, we outline the basic requirements and parameters that are important for UEM. Different types of imaging modes in UEM are analyzed and summarized. After reviewing and analyzing the different kinds of photoemission sources and beam blankers that have been reported in the literature, we estimate the reduced brightness for all the photoemission sources reviewed and compare this to the brightness in the continuous and blanked beams. As for the problem of pulse broadening caused by the repulsive forces between electrons, four main methods available to mitigate the dispersion are summarized. We anticipate that the analysis and conclusions provided in this manuscript will be instructive for designing an UEM setup and could thus push the further development of UEM.
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Affiliation(s)
| | - Jacob P Hoogenboom
- Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
| | - Ben Cook
- Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
| | - Pieter Kruit
- Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
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20
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Shaheen BS, El-Zohry AM, Yin J, De Bastiani M, De Wolf S, Bakr OM, Mohammed OF. Visualization of Charge Carrier Trapping in Silicon at the Atomic Surface Level Using Four-Dimensional Electron Imaging. J Phys Chem Lett 2019; 10:1960-1966. [PMID: 30942595 DOI: 10.1021/acs.jpclett.9b00598] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The ultrathin thickness (∼1-2 nm) of the native oxide layer on silicon surfaces, which acts as efficient trapping centers, precludes the possibility of studying its impact on the surface-charge carrier dynamics by conventional time-resolved laser spectroscopic techniques because of the large penetration depth of the pump and probe pulses. Here, we use four-dimensional scanning ultrafast electron microscopy (4D S-UEM) with unique surface sensitivity to directly visualize the charge carrier dynamics on Si(100) crystals before and after surface treatment (which removes the native oxide layer) in real space and time simultaneously. Our time-resolved snapshots of the top surface and Kelvin probe-force microscopy results demonstrate that the oxide layer can be formed within minutes after surface treatment, creating undesirable surface-trap states that destroy the population of photogenerated charge carriers on the surface and possibly at the device interface. This new surface observation provides critical photophysical insights into how a few atomic layers of oxide can dramatically influence charge carrier recombination dynamics in silicon solar cells.
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Affiliation(s)
- Basamat S Shaheen
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Ahmed M El-Zohry
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Jun Yin
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Michele De Bastiani
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Stefaan De Wolf
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Osman M Bakr
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | - Omar F Mohammed
- King Abdullah University of Science and Technology (KAUST) , Division of Physical Sciences and Engineering , Thuwal 23955-6900 , Kingdom of Saudi Arabia
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21
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Etman N, Said AMA, Atia KSR, Sultan R, Hameed MFO, Amin M, Obayya SSA. Quantum Effects In Imaging Nano-Structures Using Photon-Induced Near-Field Electron Microscopy. Sci Rep 2019; 9:6139. [PMID: 30992492 PMCID: PMC6468085 DOI: 10.1038/s41598-019-42624-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 04/02/2019] [Indexed: 11/20/2022] Open
Abstract
In this paper, we introduce the quantum mechanical approach as a more physically-realistic model to accurately quantify the electron-photon interaction in Photon-induced near-field electron microscopy (PINEM). Further, we compare the maximum coupling speed between the electrons and the photons in the quantum and classical regime. For a nanosphere of radius 2.13 nm, full quantum calculations show that the maximum coupling between photon and electron occurs at a slower speed than classical calculations report. In addition, a significant reduction in PINEM field intensity is observed for the full quantum model. Furthermore, we discuss the size limitation for particles imaged using the PIMEN technique and the role of the background material in improving the PINEM intensity. We further report a significant reduction in PINEM intensity in nearly touching plasmonic particles (0.3 nm gap) due to tunneling effect.
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Affiliation(s)
- Naglaa Etman
- Center for Photonics and Smart Materials, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt.,Electronics and Communications Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, 35516, Egypt
| | - Afaf M A Said
- Center for Photonics and Smart Materials, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt
| | - Khaled S R Atia
- Center for Photonics and Smart Materials, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt.,Advanced Research Complex, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Reem Sultan
- Electronics and Communications Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, 35516, Egypt
| | - Mohamed Farhat O Hameed
- Center for Photonics and Smart Materials, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt. .,Nanotechnolgy Engineering Program, University of Science and Technology, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt. .,Mathematics and Engineering Physics Dept., Faculty of Engineering, Mansoura University, Mansoura, 35516, Egypt.
| | - Muhamed Amin
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607, Hamburg, Germany. .,Department of Sciences, University College Groningen, Hoendiepskade 23/24, 9718, BG Groningen, Netherlands.
| | - S S A Obayya
- Center for Photonics and Smart Materials, Zewail City of Science and Technology, October Gardens, Giza, 12578, Egypt. .,Electronics and Communications Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, 35516, Egypt.
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22
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El-Zohry AM, Shaheen BS, Burlakov VM, Yin J, Hedhili MN, Shikin S, Ooi B, Bakr OM, Mohammed OF. Extraordinary Carrier Diffusion on CdTe Surfaces Uncovered by 4D Electron Microscopy. Chem 2019. [DOI: 10.1016/j.chempr.2018.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Adhikari A, Kwon OH. Surface versus Bulk: Charge Carriers Play by Different Rules. Chem 2019. [DOI: 10.1016/j.chempr.2019.02.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Centi G, Čejka J. Needs and Gaps for Catalysis in Addressing Transitions in Chemistry and Energy from a Sustainability Perspective. CHEMSUSCHEM 2019; 12:621-632. [PMID: 30648784 DOI: 10.1002/cssc.201802637] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 12/13/2018] [Indexed: 06/09/2023]
Abstract
Catalysis is undergoing a major transition resulting from significant changes in chemical and energy production. To honor the 50th anniversary of establishing the Jerzy Haber Institute of Catalysis and Surface Chemistry, this Essay discusses, from a forward-looking, personal and somewhat provocative perspective, the needs and gaps of catalysis to address the ongoing transition in chemistry and energy from a sustainability perspective. The focus is on a few selected aspects identified as crucial: i) The precise synthesis of catalytic materials, particularly focusing on mesoporous molecular sieves, metal-organic frameworks, and zeolites (particularly two-dimensional type); ii) advanced catalyst characterization methods; iii) new concepts and approaches needed in catalysis to meet the demands of a field of energy and chemistry in transition.
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Affiliation(s)
- Gabriele Centi
- University of Messina, ERIC aisbl and CASPE/INSTM, Dept.s MIFT-Industrial Chemistry, V.le F. Stagno D'Alcontres 31, 98166, Messina, Italy
| | - Jiří Čejka
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Science, Dolejškova 3, 182 23, Prague 8, Czech Republic
- Current address: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, 128 43, Prague 2, Czech Republic
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25
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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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26
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Meuret S, Solà Garcia M, Coenen T, Kieft E, Zeijlemaker H, Lätzel M, Christiansen S, Woo SY, Ra YH, Mi Z, Polman A. Complementary cathodoluminescence lifetime imaging configurations in a scanning electron microscope. Ultramicroscopy 2018; 197:28-38. [PMID: 30476703 DOI: 10.1016/j.ultramic.2018.11.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 11/09/2018] [Accepted: 11/13/2018] [Indexed: 11/29/2022]
Abstract
Cathodoluminescence (CL) spectroscopy provides a powerful way to characterize optical properties of materials with deep-subwavelength spatial resolution. While CL imaging to obtain optical spectra is a well-developed technology, imaging CL lifetimes with nanoscale resolution has only been explored in a few studies. In this paper we compare three different time-resolved CL techniques and compare their characteristics. Two configurations are based on the acquisition of CL decay traces using a pulsed electron beam that is generated either with an ultra-fast beam blanker, which is placed in the electron column, or by photoemission from a laser-driven electron cathode. The third configuration uses measurements of the autocorrelation function g(2) of the CL signal using either a continuous or a pulsed electron beam. The three techniques are compared in terms of complexity of implementation, spatial and temporal resolution, and measurement accuracy as a function of electron dose. A single sample of InGaN/GaN quantum wells is investigated to enable a direct comparison of lifetime measurement characteristics of the three techniques. The g(2)-based method provides decay measurements at the best spatial resolution, as it leaves the electron column configuration unaffected. The pulsed-beam methods provide better detail on the temporal excitation and decay dynamics. The ultra-fast blanker configuration delivers electron pulses as short as 30 ps at 5 keV and 250 ps at 30 keV. The repetition rate can be chosen arbitrarily up to 80 MHz and requires a conjugate plane geometry in the electron column that reduces the spatial resolution in our microscope. The photoemission configuration, pumped with 250 fs 257 nm pulses at a repetition rate from 10 kHz to 25 MHz, allows creation of electron pulses down to a few ps, with some loss in spatial resolution.
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Affiliation(s)
- S Meuret
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
| | - M Solà Garcia
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - T Coenen
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands; Delmic BV, Kanaalweg 4, 2628 EB Delft, The Netherlands
| | - E Kieft
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands
| | - H Zeijlemaker
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - M Lätzel
- Max Planck Institute for the Science of Light, Staudtstrasse 2, 91058 Erlangen, Germany
| | - S Christiansen
- Max Planck Institute for the Science of Light, Staudtstrasse 2, 91058 Erlangen, Germany
| | - S Y Woo
- Department of Materials Science and Engineering, Canadian Centre for Electron Microscopy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Y H Ra
- Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A 0E9, Canada
| | - Z Mi
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA
| | - A Polman
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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27
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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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28
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Barthel T, Lu J. Fundamental Limitations for Measurements in Quantum Many-Body Systems. PHYSICAL REVIEW LETTERS 2018; 121:080406. [PMID: 30192598 DOI: 10.1103/physrevlett.121.080406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 06/20/2018] [Indexed: 06/08/2023]
Abstract
Dynamical measurement schemes are an important tool for the investigation of quantum many-body systems, especially in the age of quantum simulation. Here, we address the question whether generic measurements can be implemented efficiently if we have access to a certain set of experimentally realizable measurements and can extend it through time evolution. For the latter, two scenarios are considered: (a) evolution according to unitary circuits and (b) evolution due to Hamiltonians that we can control in a time-dependent fashion. We find that the time needed to realize a certain measurement to a predefined accuracy scales in general exponentially with the system size-posing a fundamental limitation. The argument is based on the construction of ϵ-packings for manifolds of observables with identical spectra and a comparison of their cardinalities to those of ϵ-coverings for quantum circuits and unitary time-evolution operators. The former is related to the study of Grassmann manifolds.
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Affiliation(s)
- Thomas Barthel
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - Jianfeng Lu
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
- Department of Mathematics, Duke University, Durham, North Carolina 27708, USA
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29
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Kasprzak CR, Scherzinger ET, Sarkar A, Miao M, Porcincula DH, Madriz AM, Pennewell ZM, Chau SS, Fernando R, Stefik M, Zhang S. Ordered Nanostructures of Carbon Nanotube–Polymer Composites from Lyotropic Liquid Crystal Templating. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201800197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Christopher R. Kasprzak
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Evan T. Scherzinger
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Amrita Sarkar
- Department of Chemistry and Biochemistry University of South Carolina Columbia SC 29208 USA
| | - Miranda Miao
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Dominique H. Porcincula
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Alejandro M. Madriz
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Zachary M. Pennewell
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Sophia S. Chau
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Raymond Fernando
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
| | - Morgan Stefik
- Department of Chemistry and Biochemistry University of South Carolina Columbia SC 29208 USA
| | - Shanju Zhang
- Department of Chemistry and Biochemistry California Polytechnic State University San Luis Obispo CA 93407 USA
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30
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Plemmons DA, Flannigan DJ. Ultrafast electron microscopy: Instrument response from the single-electron to high bunch-charge regimes. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.01.055] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Haji-Akbari A, Debenedetti PG. Perspective: Surface freezing in water: A nexus of experiments and simulations. J Chem Phys 2017; 147:060901. [DOI: 10.1063/1.4985879] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, USA
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32
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Cremons DR, Plemmons DA, Flannigan DJ. Defect-mediated phonon dynamics in TaS 2 and WSe 2. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044019. [PMID: 28503630 PMCID: PMC5411267 DOI: 10.1063/1.4982817] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 04/19/2017] [Indexed: 05/22/2023]
Abstract
We report correlative crystallographic and morphological studies of defect-dependent phonon dynamics in single flakes of 1T-TaS2 and 2H-WSe2 using selected-area diffraction and bright-field imaging in an ultrafast electron microscope. In both materials, we observe in-plane speed-of-sound acoustic-phonon wave trains, the dynamics of which (i.e., emergence, propagation, and interference) are strongly dependent upon discrete interfacial features (e.g., vacuum/crystal and crystal/crystal interfaces). In TaS2, we observe cross-propagating in-plane acoustic-phonon wave trains of differing frequencies that undergo coherent interference approximately 200 ps after initial emergence from distinct interfacial regions. With ultrafast bright-field imaging, the properties of the interfering wave trains are observed to correspond to the beat frequency of the individual oscillations, while intensity oscillations of Bragg spots generated from selected areas within the region of interest match well with the real-space dynamics. In WSe2, distinct acoustic-phonon dynamics are observed emanating and propagating away from structurally dissimilar morphological discontinuities (vacuum/crystal interface and crystal terrace), and results of ultrafast selected-area diffraction reveal thickness-dependent phonon frequencies. The overall observed dynamics are well-described using finite element analysis and time-dependent linear-elastic continuum mechanics.
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Affiliation(s)
- Daniel R Cremons
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Dayne A Plemmons
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
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33
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Shaheen BS, Sun J, Yang DS, Mohammed OF. Spatiotemporal Observation of Electron-Impact Dynamics in Photovoltaic Materials Using 4D Electron Microscopy. J Phys Chem Lett 2017; 8:2455-2462. [PMID: 28514160 DOI: 10.1021/acs.jpclett.7b01116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding light-triggered charge carrier dynamics near photovoltaic-material surfaces and at interfaces has been a key element and one of the major challenges for the development of real-world energy devices. Visualization of such dynamics information can be obtained using the one-of-a-kind methodology of scanning ultrafast electron microscopy (S-UEM). Here, we address the fundamental issue of how the thickness of the absorber layer may significantly affect the charge carrier dynamics on material surfaces. Time-resolved snapshots indicate that the dynamics of charge carriers generated by electron impact in the electron-photon dynamical probing regime is highly sensitive to the thickness of the absorber layer, as demonstrated using CdSe films of different thicknesses as a model system. This finding not only provides the foundation for potential applications of S-UEM to a wide range of devices in the fields of chemical and materials research, but also has impact on the use and interpretation of electron beam-induced current for optimization of photoactive materials in these devices.
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Affiliation(s)
- Basamat S Shaheen
- KAUST Solar Center, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Jingya Sun
- KAUST Solar Center, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Ding-Shyue Yang
- Department of Chemistry, University of Houston , Houston, Texas 77204, United States
| | - Omar F Mohammed
- KAUST Solar Center, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
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