1
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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Tong L, Li D, Su T, Gao S, Wang P, Tang J, Wang ZL, Shi K, Wang ZW. Direct mapping of bending and torsional dynamics in individual nanostructures. Proc Natl Acad Sci U S A 2023; 120:e2221956120. [PMID: 37307491 DOI: 10.1073/pnas.2221956120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/10/2023] [Indexed: 06/14/2023] Open
Abstract
Investigating coherent acoustic vibrations in nanostructured materials provides fundamental insights into optomechanical responses and microscopic energy flow. Extensive measurements of vibrational dynamics have been performed for a wide variety of nanoparticles and nanoparticle assemblies. However, virtually all of them show that only the dilation modes are launched after laser excitations, and the acoustic bending and torsional motions, which are commonly observed in photoexcited chemical bonds, are absent. Unambiguous identification and refined characterization of these "missing" modes have been a long-standing issue. In this report, we investigated the acoustic vibrational dynamics of individual Au nanoprisms on free-standing graphene substrates using an ultrafast high-sensitivity dark-field imaging approach in four-dimensional transmission electron microscopy. Following optical excitations, we observed low-frequency multiple-mode oscillations and higher superposition amplitudes at nanoprism corners and edges on the subnanoparticle level. In combination with finite-element simulations, we determined that these vibrational modes correspond to out-of-plane bending and torsional motions, superimposed by an overall tilting effect of the nanoprisms. The launch and relaxation processes of these modes are highly pertinent to substrate effects and nanoparticle geometries. These findings contribute to the fundamental understanding about acoustic dynamics of individual nanostructures and their interaction with substrates.
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Affiliation(s)
- Ling Tong
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deshuai Li
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ting Su
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Si Gao
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Peng Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Jau Tang
- The Institute for Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Zhong Lin Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245
| | - Kebin Shi
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Zhi Wei Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
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3
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Wöste A, Hergert G, Quenzel T, Silies M, Wang D, Groß P, Lienau C. Ultrafast Coupling of Optical Near Fields to Low-Energy Electrons Probed in a Point-Projection Microscope. Nano Lett 2023. [PMID: 37278447 DOI: 10.1021/acs.nanolett.3c00738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the first observation of the coupling of strong optical near fields to wavepackets of free, 100 eV electrons with <50 fs temporal resolution in an ultrafast point-projection microscope. Optical near fields are created by excitation of a thin, nanometer-sized Yagi-Uda antenna, with 20 fs near-infrared laser pulses. Phase matching between electrons and near fields is achieved due to strong spatial confinement of the antenna near field. Energy-resolved projection images of the antenna are recorded in an optical pump-electron probe scheme. We show that the phase modulation of the electron by transverse-field components results in a transient electron deflection while longitudinal near-field components broaden the kinetic energy distribution. This low-energy electron near-field coupling is used here to characterize the chirp of the ultrafast electron wavepackets, acquired upon propagation from the electron emitter to the sample. Our results bring direct mapping of different vectorial components of highly localized optical near fields into reach.
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Affiliation(s)
- Andreas Wöste
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Germann Hergert
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Thomas Quenzel
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Martin Silies
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Dong Wang
- Institut für Werkstofftechnik und Institut für Mikro- und Nanotechnologien, TU Ilmenau, 98693 Ilmenau, Germany
| | - Petra Groß
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Christoph Lienau
- Institut für Physik und Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität, 26129 Oldenburg, Germany
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4
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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5
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Morimoto Y. Attosecond electron-beam technology: a review of recent progress. Microscopy (Oxf) 2023; 72:2-17. [PMID: 36269108 DOI: 10.1093/jmicro/dfac054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/14/2022] [Accepted: 10/20/2022] [Indexed: 11/13/2022] Open
Abstract
Electron microscopy and diffraction with ultrashort pulsed electron beams are capable of imaging transient phenomena with the combined ultrafast temporal and atomic-scale spatial resolutions. The emerging field of optical electron beam control allowed the manipulation of relativistic and sub-relativistic electron beams at the level of optical cycles. Specifically, it enabled the generation of electron beams in the form of attosecond pulse trains and individual attosecond pulses. In this review, we describe the basics of the attosecond electron beam control and overview the recent experimental progress. High-energy electron pulses of attosecond sub-optical cycle duration open up novel opportunities for space-time-resolved imaging of ultrafast chemical and physical processes, coherent photon generation, free electron quantum optics, electron-atom scattering with shaped wave packets and laser-driven particle acceleration. Graphical Abstract.
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Affiliation(s)
- Yuya Morimoto
- Ultrashort Electron Beam Science RIKEN Hakubi research team, RIKEN Cluster for Pioneering Research (CPR), RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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6
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Du DX, Fitzpatrick AW. Design of an ultrafast pulsed ponderomotive phase plate for cryo-electron tomography. Cell Rep Methods 2023; 3:100387. [PMID: 36814846 PMCID: PMC9939428 DOI: 10.1016/j.crmeth.2022.100387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/09/2022] [Accepted: 12/20/2022] [Indexed: 01/15/2023]
Abstract
Ponderomotive phase plates have shown that temporally consistent phase contrast is possible within electron microscopes via high-fluence static laser modes resonating in Fabry-Perot cavities. Here, we explore using pulsed laser beams as an alternative method of generating high fluences. We find through forward-stepping finite element models that picosecond or shorter interactions are required for meaningful fluences and phase shifts, with higher pulse energies and smaller beam waists leading to predicted higher fluences. An additional model based on quasi-classical assumptions is used to discover the shape of the phase plate by incorporating the oscillatory nature of the electric field. From these results, we find the transient nature of the laser pulses removes the influence of Kapitza-Dirac diffraction patterns that appear in the static resonator cases. We conclude by predicting that a total laser pulse energy of 8.7 μJ is enough to induce the required π/2 phase shift for Zernike-like phase microscopy.
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Affiliation(s)
- Daniel X. Du
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, 630 West 168th Street, New York, NY 10032, USA
| | - Anthony W.P. Fitzpatrick
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, 630 West 168th Street, New York, NY 10032, USA
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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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Hu Y, Picher M, Tran NM, Palluel M, Stoleriu L, Daro N, Mornet S, Enachescu C, Freysz E, Banhart F, Chastanet G. Photo-Thermal Switching of Individual Plasmonically Activated Spin Crossover Nanoparticle Imaged by Ultrafast Transmission Electron Microscopy. Adv Mater 2021; 33:e2105586. [PMID: 34601766 DOI: 10.1002/adma.202105586] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Spin crossover (SCO) is a promising switching phenomenon when implemented in electronic devices as molecules, thin films or nanoparticles. Among the properties modulated along this phenomenon, optically induced mechanical changes are of tremendous importance as they can work as fast light-induced mechanical switches or allow to investigate and control microstructural strains and fatigability. The development of characterization techniques probing nanoscopic behavior with high spatio-temporal resolution allows to trigger and visualize such mechanical changes of individual nanoscopic objects. Here, ultrafast transmission electron microscopy (UTEM) is used to precisely probe the length changes of individual switchable nanoparticles induced thermally by nanosecond laser pulses. This allows revealing of the mechanisms of spin switching, leading to the macroscopic expansion of SCO materials. This study is conducted on individual pure SCO nanoparticles and SCO nanoparticles encapsulating gold nanorods that serve for plasmonic heating under laser pulses. Length changes are compared with time-resolved optical measurements performed on an assembly of these particles.
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Affiliation(s)
- Yaowei Hu
- Institut de Physique et Chimie des Matériaux, UMR 7504 CNRS, Université de Strasbourg, Strasbourg, F-67034, France
| | - Matthieu Picher
- Institut de Physique et Chimie des Matériaux, UMR 7504 CNRS, Université de Strasbourg, Strasbourg, F-67034, France
| | - Ngoc Minh Tran
- Universite de Bordeaux, CNRS, UMR 5798, LOMA, 358 Cours de la libération, Talence cedex, F-33405, France
| | - Marlène Palluel
- Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux, Bordeaux INP, UMR 5026, Pessac, F-33600, France
| | - Laurentiu Stoleriu
- Faculty of Physics, Alexandru Ioan Cuza University, Iasi, 700506, Romania
| | - Nathalie Daro
- Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux, Bordeaux INP, UMR 5026, Pessac, F-33600, France
| | - Stephane Mornet
- Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux, Bordeaux INP, UMR 5026, Pessac, F-33600, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University, Iasi, 700506, Romania
| | - Eric Freysz
- Universite de Bordeaux, CNRS, UMR 5798, LOMA, 358 Cours de la libération, Talence cedex, F-33405, France
| | - Florian Banhart
- Institut de Physique et Chimie des Matériaux, UMR 7504 CNRS, Université de Strasbourg, Strasbourg, F-67034, France
| | - Guillaume Chastanet
- Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux, Bordeaux INP, UMR 5026, Pessac, F-33600, France
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9
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Kim T, Oh S, Choudhry U, Meinhart CD, Chabinyc ML, Liao B. Transient Strain-Induced Electronic Structure Modulation in a Semiconducting Polymer Imaged by Scanning Ultrafast Electron Microscopy. Nano Lett 2021; 21:9146-9152. [PMID: 34672604 DOI: 10.1021/acs.nanolett.1c02963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding the optoelectronic properties of semiconducting polymers under external strain is essential for their applications in flexible devices. Although prior studies have highlighted the impact of static and macroscopic strains, assessing the effect of a local transient deformation before structural relaxation occurs remains challenging. Here, we employ scanning ultrafast electron microscopy (SUEM) to image the dynamics of a photoinduced transient strain in the semiconducting polymer poly(3-hexylthiophene) (P3HT). We observe that the photoinduced SUEM contrast, corresponding to the local change of secondary electron emission, exhibits an unusual ring-shaped profile. We attribute the observation to the electronic structure modulation of P3HT caused by a photoinduced strain field owing to its low modulus and strong electron-lattice coupling, supported by a finite-element analysis. Our work provides insights into tailoring optoelectronic properties using transient mechanical deformation in semiconducting polymers and demonstrates the versatility of SUEM to study photophysical processes in diverse materials.
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Affiliation(s)
- Taeyong Kim
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Saejin Oh
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Usama Choudhry
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Carl D Meinhart
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Michael L Chabinyc
- Materials Department, University of California, Santa Barbara, California 93106, United States
| | - Bolin Liao
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, United States
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10
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Liu H, Gage TE, Singh P, Jaiswal A, Schaller RD, Tang J, Park ST, Gray SK, Arslan I. Visualization of Plasmonic Couplings Using Ultrafast Electron Microscopy. Nano Lett 2021; 21:5842-5849. [PMID: 34153185 DOI: 10.1021/acs.nanolett.1c01824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Hybrids of graphene and metal plasmonic nanostructures are promising building blocks for applications in optoelectronics, surface-enhanced scattering, biosensing, and quantum information. An understanding of the coupling mechanism in these hybrid systems is of vital importance to its applications. Previous efforts in this field mainly focused on spectroscopic studies of strong coupling within the hybrids with no spatial resolution. Here we report direct imaging of the local plasmonic coupling between single Au nanocapsules and graphene step edges at the nanometer scale by photon-induced near-field electron microscopy in an ultrafast electron microscope for the first time. The proximity of a step in the graphene to the nanocapsule causes asymmetric surface charge density at the ends of the nanocapsules. Computational electromagnetic simulations confirm the experimental observations. The results reported here indicate that this hybrid system could be used to manipulate the localized electromagnetic field on the nanoscale, enabling promising future plasmonic devices.
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Affiliation(s)
- Haihua Liu
- 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
| | - Prem Singh
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India
| | - Amit Jaiswal
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India
| | - Richard D Schaller
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Jau Tang
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Sang Tae Park
- IDES, Inc. (a JEOL company), Pleasanton, California 94588, United States
| | - Stephen K Gray
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ilke Arslan
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
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11
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Di Giulio V, Kfir O, Ropers C, García de Abajo FJ. Modulation of Cathodoluminescence Emission by Interference with External Light. ACS Nano 2021; 15:7290-7304. [PMID: 33724007 PMCID: PMC8939848 DOI: 10.1021/acsnano.1c00549] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 02/18/2021] [Indexed: 05/20/2023]
Abstract
Spontaneous processes triggered in a sample by free electrons, such as cathodoluminescence, are commonly regarded and detected as stochastic events. Here, we supplement this picture by showing through first-principles theory that light and free-electron pulses can interfere when interacting with a nanostructure, giving rise to a modulation in the spectral distribution of the cathodoluminescence light emission that is strongly dependent on the electron wave function. Specifically, for a temporally focused electron, cathodoluminescence can be canceled upon illumination with a spectrally modulated dimmed laser that is phase-locked relative to the electron density profile. We illustrate this idea with realistic simulations under attainable conditions in currently available ultrafast electron microscopes. We further argue that the interference between excitations produced by light and free electrons enables the manipulation of the ultrafast materials response by combining the spectral and temporal selectivity of the light with the atomic resolution of electron beams.
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Affiliation(s)
- Valerio Di Giulio
- ICFO-Institut de
Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| | - Ofer Kfir
- IV Physical Institute,
Solids and Nanostructures, University of
Göttingen, 37077 Göttingen, Germany
- Max Planck
Institute for Biophysical Chemistry (MPIBPC), 37077 Göttingen, Germany
| | - Claus Ropers
- IV Physical Institute,
Solids and Nanostructures, University of
Göttingen, 37077 Göttingen, Germany
- Max Planck
Institute for Biophysical Chemistry (MPIBPC), 37077 Göttingen, Germany
| | - 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
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12
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VandenBussche EJ, Flannigan DJ. High-resolution analogue of time-domain phonon spectroscopy in the transmission electron microscope. Philos Trans A Math Phys Eng Sci 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] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Solà-Garcia M, Meuret S, Coenen T, Polman A. Electron-Induced State Conversion in Diamond NV Centers Measured with Pump-Probe Cathodoluminescence Spectroscopy. ACS Photonics 2020; 7:232-240. [PMID: 31976357 PMCID: PMC6967233 DOI: 10.1021/acsphotonics.9b01463] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 05/20/2023]
Abstract
Nitrogen-vacancy (NV) centers in diamond are reliable single-photon emitters, with applications in quantum technologies and metrology. Two charge states are known for NV centers, NV0 and NV-, with the latter being mostly studied due to its long electron spin coherence time. Therefore, control over the charge state of the NV centers is essential. However, an understanding of the dynamics between the different states still remains challenging. Here, conversion from NV- to NV0 due to electron-induced carrier generation is shown. Ultrafast pump-probe cathodoluminescence spectroscopy is presented for the first time, with electron pulses as pump and laser pulses as probe, to prepare and read out the NV states. The experimental data are explained with a model considering carrier dynamics (0.8 ns), NV0 spontaneous emission (20 ns), and NV0 → NV- back transfer (500 ms). The results provide new insights into the NV- → NV0 conversion dynamics and into the use of pump-probe cathodoluminescence as a nanoscale NV characterization tool.
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Affiliation(s)
- Magdalena Solà-Garcia
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands
- E-mail:
| | - Sophie Meuret
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands
| | - Toon Coenen
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands
- Delmic
BV, Kanaalweg 4, 2628 EB, Delft, The Netherlands
| | - Albert Polman
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands
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15
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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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Abstract
Despite the development of a myriad of mitigation methods, radiation damage continues to be a major limiting factor in transmission electron microscopy. Intriguing results have been reported using pulsed-laser driven and chopped electron beams for modulated dose delivery, but the underlying relationships and effects remain unclear. Indeed, delivering precisely timed single-electron packets to the specimen has yet to be systematically explored, and no direct comparisons to conventional methods within a common parameter space have been made. Here, using a model linear saturated hydrocarbon (n-hexatriacontane, C36H74), we show that precisely timed delivery of each electron to the specimen, with a well-defined and uniform time between arrival, leads to a repeatable reduction in damage compared to conventional ultralow-dose methods for the same dose rate and the same accumulated dose. Using a femtosecond pulsed laser to confine the probability of electron emission to a 300 fs temporal window, we find damage to be sensitively dependent on the time between electron arrival (controlled with the laser repetition rate) and on the number of electrons per packet (controlled with the laser-pulse energy). Relative arrival times of 5, 20, and 100 μs were tested for electron packets comprised of, on average, 1, 5, and 20 electrons. In general, damage increased with decreasing time between electrons and, more substantially, with increasing electron number. Further, we find that improvements relative to conventional methods vanish once a threshold number of electrons per packet is reached. The results indicate that precise electron-by-electron dose delivery leads to a repeatable reduction in irreversible structural damage, and the systematic studies indicate this arises from control of the time between sequential electrons arriving within the same damage radius, all else being equal.
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Affiliation(s)
- Elisah J VandenBussche
- 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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17
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Liao B, Zhao H, Najafi E, Yan X, Tian H, Tice J, Minnich AJ, Wang H, Zewail AH. Spatial-Temporal Imaging of Anisotropic Photocarrier Dynamics in Black Phosphorus. Nano Lett 2017; 17:3675-3680. [PMID: 28505461 DOI: 10.1021/acs.nanolett.7b00897] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
As an emerging single elemental layered material with a low symmetry in-plane crystal lattice, black phosphorus (BP) has attracted significant research interest owing to its unique electronic and optoelectronic properties, including its widely tunable bandgap, polarization-dependent photoresponse and highly anisotropic in-plane charge transport. Despite extensive study of the steady-state charge transport in BP, there has not been direct characterization and visualization of the hot carriers dynamics in BP immediately after photoexcitation, which is crucial to understanding the performance of BP-based optoelectronic devices. Here we use the newly developed scanning ultrafast electron microscopy (SUEM) to directly visualize the motion of photoexcited hot carriers on the surface of BP in both space and time. We observe highly anisotropic in-plane diffusion of hot holes with a 15 times higher diffusivity along the armchair (x-) direction than that along the zigzag (y-) direction. Our results provide direct evidence of anisotropic hot carrier transport in BP and demonstrate the capability of SUEM to resolve ultrafast hot carrier dynamics in layered two-dimensional materials.
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Affiliation(s)
| | - Huan Zhao
- Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States
| | | | - Xiaodong Yan
- Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States
| | - He Tian
- Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States
| | - Jesse Tice
- NG Next, Northrop Grumman, 1 Space Park, Redondo Beach, California 90278, United States
| | - Austin J Minnich
- Division of Engineering and Applied Science, California Institute of Technology , Pasadena, California 91125, United States
| | - Han Wang
- Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States
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18
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Bose R, Sun J, Khan JI, Shaheen BS, Adhikari A, Ng TK, Burlakov VM, Parida MR, Priante D, Goriely A, Ooi BS, Bakr OM, Mohammed OF. Real-Space Visualization of Energy Loss and Carrier Diffusion in a Semiconductor Nanowire Array Using 4D Electron Microscopy. Adv Mater 2016; 28:5106-5111. [PMID: 27111855 DOI: 10.1002/adma.201600202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 02/28/2016] [Indexed: 06/05/2023]
Abstract
A breakthrough in the development of 4D scanning ultrafast electron microscopy is described for real-time and space imaging of secondary electron energy loss and carrier diffusion on the surface of an array of nanowires as a model system, providing access to a territory that is beyond the reach of either static electron imaging or any time-resolved laser spectroscopy.
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Affiliation(s)
- Riya Bose
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Jingya Sun
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Jafar I Khan
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Basamat S Shaheen
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Aniruddha Adhikari
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Tien Khee Ng
- Photonics Laboratory, Computer, Electrical, and Mathematical Sciences and Engineering, KAUST, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Victor M Burlakov
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK
| | - Manas R Parida
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Davide Priante
- Photonics Laboratory, Computer, Electrical, and Mathematical Sciences and Engineering, KAUST, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK
| | - Boon S Ooi
- Photonics Laboratory, Computer, Electrical, and Mathematical Sciences and Engineering, KAUST, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Osman M Bakr
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Omar F Mohammed
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
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19
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Yoo BK, Su Z, Thomas JM, Zewail AH. On the dynamical nature of the active center in a single-site photocatalyst visualized by 4D ultrafast electron microscopy. Proc Natl Acad Sci U S A 2016; 113:503-8. [PMID: 26729878 DOI: 10.1073/pnas.1522869113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the dynamical nature of the catalytic active site embedded in complex systems at the atomic level is critical to developing efficient photocatalytic materials. Here, we report, using 4D ultrafast electron microscopy, the spatiotemporal behaviors of titanium and oxygen in a titanosilicate catalytic material. The observed changes in Bragg diffraction intensity with time at the specific lattice planes, and with a tilted geometry, provide the relaxation pathway: the Ti(4+)=O(2-) double bond transformation to a Ti(3+)-O(1-) single bond via the individual atomic displacements of the titanium and the apical oxygen. The dilation of the double bond is up to 0.8 Å and occurs on the femtosecond time scale. These findings suggest the direct catalytic involvement of the Ti(3+)-O(1-) local structure, the significance of nonthermal processes at the reactive site, and the efficient photo-induced electron transfer that plays a pivotal role in many photocatalytic reactions.
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20
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Sun J, Melnikov VA, Khan JI, Mohammed OF. Real-Space Imaging of Carrier Dynamics of Materials Surfaces by Second-Generation Four-Dimensional Scanning Ultrafast Electron Microscopy. J Phys Chem Lett 2015; 6:3884-3890. [PMID: 26722888 DOI: 10.1021/acs.jpclett.5b01867] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In the fields of photocatalysis and photovoltaics, ultrafast dynamical processes, including carrier trapping and recombination on material surfaces, are among the key factors that determine the overall energy conversion efficiency. A precise knowledge of these dynamical events on the nanometer (nm) and femtosecond (fs) scales was not accessible until recently. The only way to access such fundamental processes fully is to map the surface dynamics selectively in real space and time. In this study, we establish a second generation of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ∼5 nm temporal and spatial resolutions, respectively. In this method, the surface of a specimen is excited by a clocking optical pulse and imaged using a pulsed primary electron beam as a probe pulse, generating secondary electrons (SEs), which are emitted from the surface of the specimen in a manner that is sensitive to the local electron/hole density. This method provides direct and controllable information regarding surface dynamics. We clearly demonstrate how the surface morphology, grains, defects, and nanostructured features can significantly impact the overall dynamical processes on the surface of photoactive-materials. In addition, the ability to access two regimes of dynamical probing in a single experiment and the energy loss of SEs in semiconductor-nanoscale materials will also be discussed.
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Affiliation(s)
- Jingya Sun
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Vasily A Melnikov
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Jafar I Khan
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Omar F Mohammed
- Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
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21
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Vogelsang J, Robin J, Nagy BJ, Dombi P, Rosenkranz D, Schiek M, Groß P, Lienau C. Ultrafast Electron Emission from a Sharp Metal Nanotaper Driven by Adiabatic Nanofocusing of Surface Plasmons. Nano Lett 2015; 15:4685-91. [PMID: 26061633 DOI: 10.1021/acs.nanolett.5b01513] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We report photoelectron emission from the apex of a sharp gold nanotaper illuminated via grating coupling at a distance of 50 μm from the emission site with few-cycle near-infrared laser pulses. We find a fifty-fold increase in electron yield over that for direct apex illumination. Spatial localization of the electron emission to a nanometer-sized region is demonstrated by point-projection microscopic imaging of a silver nanowire. Our results reveal negligible plasmon-induced electron emission from the taper shaft and thus efficient nanofocusing of few-cycle plasmon wavepackets. This novel, remotely driven emission scheme offers a particularly compact source of ultrashort electron pulses of immediate interest for miniaturized electron microscopy and diffraction schemes with ultrahigh time resolution.
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Affiliation(s)
- Jan Vogelsang
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
- ‡Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Jörg Robin
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
- ‡Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Benedek J Nagy
- §Wigner Research Centre for Physics, 1121 Budapest, Hungary
- ∥Institute of Physics, University of Pécs, 7622 Pécs, Hungary
| | - Péter Dombi
- §Wigner Research Centre for Physics, 1121 Budapest, Hungary
| | - Daniel Rosenkranz
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Manuela Schiek
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Petra Groß
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
- ‡Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
| | - Christoph Lienau
- †Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
- ‡Center of Interface Science, Carl von Ossietzky Universität, 26129 Oldenburg, Germany
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22
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Kwon OH, Barwick B, Park HS, Baskin JS, Zewail AH. 4D visualization of embryonic, structural crystallization by single-pulse microscopy. Proc Natl Acad Sci U S A 2008; 105:8519-24. [PMID: 18562291 PMCID: PMC2438388 DOI: 10.1073/pnas.0803344105] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Indexed: 11/18/2022] Open
Abstract
In many physical and biological systems the transition from an amorphous to ordered native structure involves complex energy landscapes, and understanding such transformations requires not only their thermodynamics but also the structural dynamics during the process. Here, we extend our 4D visualization method with electron imaging to include the study of irreversible processes with a single pulse in the same ultrafast electron microscope (UEM) as used before in the single-electron mode for the study of reversible processes. With this augmentation, we report on the transformation of amorphous to crystalline structure with silicon as an example. A single heating pulse was used to initiate crystallization from the amorphous phase while a single packet of electrons imaged selectively in space the transformation as the structure continuously changes with time. From the evolution of crystallinity in real time and the changes in morphology, for nanosecond and femtosecond pulse heating, we describe two types of processes, one that occurs at early time and involves a nondiffusive motion and another that takes place on a longer time scale. Similar mechanisms of two distinct time scales may perhaps be important in biomolecular folding.
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Affiliation(s)
- Oh-Hoon Kwon
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - Brett Barwick
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - Hyun Soon Park
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - J. Spencer Baskin
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
| | - Ahmed H. Zewail
- Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125
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