1
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Axelrod JJ, Zhang JT, Petrov PN, Glaeser RM, Müller H. Modern approaches to improving phase contrast electron microscopy. Curr Opin Struct Biol 2024; 86:102805. [PMID: 38531188 DOI: 10.1016/j.sbi.2024.102805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 03/04/2024] [Accepted: 03/05/2024] [Indexed: 03/28/2024]
Abstract
Although defocus can be used to generate partial phase contrast in transmission electron microscope images, cryo-electron microscopy (cryo-EM) can be further improved by the development of phase plates which increase contrast by applying a phase shift to the unscattered part of the electron beam. Many approaches have been investigated, including the ponderomotive interaction between light and electrons. We review the recent successes achieved with this method in high-resolution, single-particle cryo-EM. We also review the status of using pulsed or near-field enhanced laser light as alternatives, along with approaches that use scanning transmission electron microscopy (STEM) with a segmented detector rather than a phase plate.
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Affiliation(s)
- Jeremy J Axelrod
- Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA; Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Jessie T Zhang
- Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA
| | - Petar N Petrov
- Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA; Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Robert M Glaeser
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Holger Müller
- Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA; Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA.
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2
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Weber J, Schäfer S. Electron Imaging of Nanoscale Charge Distributions Induced by Femtosecond Light Pulses. NANO LETTERS 2024; 24:5746-5753. [PMID: 38701367 PMCID: PMC11100287 DOI: 10.1021/acs.nanolett.4c00773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 05/05/2024]
Abstract
Surface charging is ubiquitously observable during in situ transmission electron microscopy of nonconducting specimens as a result of electron beam/sample interactions or optical stimuli and often limits the achievable image stability and spatial or spectral resolution. Here, we report on the electron-optical imaging of surface charging on a nanostructured surface following femtosecond multiphoton photoemission. By quantitatively extracting the light-induced electrostatic potential and studying the charging dynamics on relevant time scales, we gain insights into the details of the multiphoton photoemission process in the presence of an electrostatic background field. We study the interaction of the charge distribution with the high-energy electron beam and secondary electrons and propose a simple model to describe the interplay of electron- and light-induced processes. In addition, we demonstrate how to mitigate sample charging by simultaneously optically illuminating the sample.
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Affiliation(s)
- Jonathan
T. Weber
- Institute
of Physics, Carl-von-Ossietzky University
of Oldenburg, 26129 Oldenburg, Germany
- Department
of Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Sascha Schäfer
- Institute
of Physics, Carl-von-Ossietzky University
of Oldenburg, 26129 Oldenburg, Germany
- Department
of Physics, University of Regensburg, 93053 Regensburg, Germany
- Regensburg
Center for Ultrafast Nanoscopy (RUN), University
of Regensburg, 93053 Regensburg, Germany
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3
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Brückner L, Nauk C, Dienstbier P, Gerner C, Löhrl B, Paschen T, Hommelhoff P. A Gold Needle Tip Array Ultrafast Electron Source with High Beam Quality. NANO LETTERS 2024. [PMID: 38620149 DOI: 10.1021/acs.nanolett.4c00870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Electron sources are crucial elements in diverse applications such as electron microscopes, synchrotrons, and free-electron lasers. Nanometer-sharp needle tips are electron emitters with the highest beam quality, yet for a single needle the current is limited. Combining the emission of multiple needles promises large current yields while preserving the individual emitters' favorable properties. We present an ultrafast electron source consisting of a lithographically fabricated array of sharp gold tips illuminated with 25 fs laser pulses. The source provides up to 2000 electrons per pulse for moderate laser peak intensities of 1011 W/cm2 and a narrow energy width of 0.5 ± 0.05 eV at low current. The electron beam has a well-behaved Gaussian profile and is highly collimated, yielding a small normalized emittance on the order of nm·rad. These properties are well suited for applications requiring both high current and spatial resolution, such as free-electron light sources and chip-based particle accelerators.
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Affiliation(s)
- Leon Brückner
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Constantin Nauk
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Philip Dienstbier
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Constanze Gerner
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Bastian Löhrl
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Timo Paschen
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Peter Hommelhoff
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
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4
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Haugg S, Makumi S, Velten S, Zierold R, Aksamija Z, Blick RH. Thermally Driven Field Emission from Zinc Oxide Wires on a Nanomembrane Used as a Detector for Time-of-Flight Mass Spectrometry. ACS OMEGA 2024; 9:10602-10609. [PMID: 38463327 PMCID: PMC10918783 DOI: 10.1021/acsomega.3c08932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/16/2024] [Accepted: 02/07/2024] [Indexed: 03/12/2024]
Abstract
Mass spectrometry is a crucial technology in numerous applications, but it places stringent requirements on the detector to achieve high resolution across a broad spectrum of ion masses. Low-dimensional nanostructures offer opportunities to tailor properties and achieve performance not reachable in bulk materials. Here, an array of sharp zinc oxide wires was directly grown on a 30 nm thin, free-standing silicon nitride nanomembrane to enhance its field emission (FE). The nanomembrane was subsequently used as a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry detector. When ionized biomolecules impinge on the backside of the surface-modified nanomembrane, the current-emitted from the wires on the membrane's front side-is amplified by the supplied thermal energy, which allows for the detection of the ions. An extensive simulation framework was developed based on a combination of lateral heat diffusion in the nanomembrane, heat diffusion along the wires, and FE, including Schottky barrier lowering, to investigate the impact of wire length and diameter on the FE. Our theoretical model suggests a significant improvement in the overall FE response of the nanomembrane by growing wires on top. Specifically, long thin wires are ideal to enhance the magnitude of the FE signal and to shorten its duration for the fastest response simultaneously, which could facilitate the future application of detectors in mass spectrometry with properties improved by low-dimensional nanostructures.
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Affiliation(s)
- Stefanie Haugg
- Center
for Hybrid Nanostructures (CHyN), Universität
Hamburg, 22761 Hamburg, Germany
| | - Sylvester Makumi
- Materials
Science and Engineering Department, University
of Utah, Salt Lake City, 84112 Utah, United States
| | - Sven Velten
- Deutsches
Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- The
Hamburg Centre for Ultrafast Imaging CUI, 22761 Hamburg, Germany
| | - Robert Zierold
- Center
for Hybrid Nanostructures (CHyN), Universität
Hamburg, 22761 Hamburg, Germany
| | - Zlatan Aksamija
- Materials
Science and Engineering Department, University
of Utah, Salt Lake City, 84112 Utah, United States
| | - Robert H. Blick
- Center
for Hybrid Nanostructures (CHyN), Universität
Hamburg, 22761 Hamburg, Germany
- Materials
Science and Engineering, College of Engineering, University of Wisconsin–Madison, Madison, 53706 Wisconsin, United States
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5
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Auad Y, Baaboura J, Blazit JD, Tencé M, Stéphan O, Kociak M, Tizei LHG. Time calibration studies for the Timepix3 hybrid pixel detector in electron microscopy. Ultramicroscopy 2024; 257:113889. [PMID: 38056397 DOI: 10.1016/j.ultramic.2023.113889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/13/2023] [Accepted: 11/23/2023] [Indexed: 12/08/2023]
Abstract
Direct electron detection is currently revolutionizing many fields of electron microscopy due to its lower noise, its reduced point-spread function, and its increased quantum efficiency. More specifically to this work, Timepix3 is a hybrid-pixel direct electron detector capable of outputting temporal information of individual hits in its pixel array. Its architecture results in a data-driven detector, also called event-based, in which individual hits trigger the data off the chip for readout as fast as possible. The presence of a pixel threshold value results in an almost readout-noise-free detector while also defining the hit time of arrival and the time the signal stays over the pixel threshold. In this work, we have performed various experiments to calibrate and correct the Timepix3 temporal information, specifically in the context of electron microscopy. These include the energy calibration, and the time-walk and pixel delay corrections, reaching an average temporal resolution throughout the entire pixel matrix of 1.37±0.04ns. Additionally, we have also studied cosmic rays tracks to characterize the charge dynamics along the volume of the sensor layer, allowing us to estimate the limits of the detector's temporal response depending on different bias voltages, sensor thickness, and the electron beam ionization volume. We have estimated the uncertainty due to the ionization volume ranging from about 0.8 ns for 60 keV electrons to 8.8 ns for 300 keV electrons.
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Affiliation(s)
- Yves Auad
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France.
| | - Jassem Baaboura
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
| | - Jean-Denis Blazit
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
| | - Marcel Tencé
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
| | - Odile Stéphan
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
| | - Mathieu Kociak
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
| | - Luiz H G Tizei
- Laboratoire des Physique des Solides, Université Paris Saclay, Orsay, France
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6
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Dang Z, Chen Y, Fang Z. Cathodoluminescence Nanoscopy: State of the Art and Beyond. ACS NANO 2023; 17:24431-24448. [PMID: 38054434 DOI: 10.1021/acsnano.3c07593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Cathodoluminescence (CL) nanoscopy is proven to be a powerful tool to explore nanoscale optical properties, whereby free electron beams achieve a spatial resolution far beyond the diffraction limit of light. With developed methods for the control of electron beams and the collection of light, the dimension of information that CL can access has been expanded to include polarization, momentum, and time, holding promise to provide invaluable insights into the study of materials and optical near-field dynamics. With a focus on the burgeoning field of CL nanoscopy, this perspective outlines the recent advancements and applications of this technique, as illustrated by the salient experimental works. In addition, as an outlook for future research, several appealing directions that may bring about developments and discoveries are highlighted.
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Affiliation(s)
- Zhibo Dang
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
| | - Yuxiang Chen
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
| | - Zheyu Fang
- School of Physics, State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, and Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, People's Republic of China
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7
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Schröder A, Rathje C, van Velzen L, Kelder M, Schäfer S. Improving the temporal resolution of event-based electron detectors using neural network cluster analysis. Ultramicroscopy 2023; 256:113881. [PMID: 37976972 DOI: 10.1016/j.ultramic.2023.113881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 10/16/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
Novel event-based electron detector platforms provide an avenue to extend the temporal resolution of electron microscopy into the ultrafast domain. Here, we characterize the timing accuracy of a detector based on a TimePix3 architecture using femtosecond electron pulse trains as a reference. With a large dataset of event clusters triggered by individual incident electrons, a neural network is trained to predict the electron arrival time. Corrected timings of event clusters show a temporal resolution of 2 ns, a 1.6-fold improvement over cluster-averaged timings. This method is applicable to other fast electron detectors down to sub-nanosecond temporal resolutions, offering a promising solution to enhance the precision of electron timing for various electron microscopy applications.
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Affiliation(s)
- Alexander Schröder
- Institute of Physics, University of Oldenburg, Oldenburg, Germany; Department of Physics, University of Regensburg, Regensburg, Germany
| | | | - Leon van Velzen
- Amsterdam Scientific Instruments (ASI), Amsterdam, the Netherlands
| | - Maurits Kelder
- Amsterdam Scientific Instruments (ASI), Amsterdam, the Netherlands
| | - Sascha Schäfer
- Institute of Physics, University of Oldenburg, Oldenburg, Germany; Department of Physics, University of Regensburg, Regensburg, Germany; Regensburg Center for Ultrafast Nanoscopy, University of Regensburg, Regensburg, Germany.
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8
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Domröse T, Danz T, Schaible SF, Rossnagel K, Yalunin SV, Ropers C. Light-induced hexatic state in a layered quantum material. NATURE MATERIALS 2023; 22:1345-1351. [PMID: 37414945 PMCID: PMC10627829 DOI: 10.1038/s41563-023-01600-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 06/05/2023] [Indexed: 07/08/2023]
Abstract
The tunability of materials properties by light promises a wealth of future applications in energy conversion and information technology. Strongly correlated materials such as transition metal dichalcogenides offer optical control of electronic phases, charge ordering and interlayer correlations by photodoping. Here, we find the emergence of a transient hexatic state during the laser-induced transformation between two charge-density wave phases in a thin-film transition metal dichalcogenide, 1T-type tantalum disulfide (1T-TaS2). Introducing tilt-series ultrafast nanobeam electron diffraction, we reconstruct charge-density wave rocking curves at high momentum resolution. An intermittent suppression of three-dimensional structural correlations promotes a loss of in-plane translational order caused by a high density of unbound topological defects, characteristic of a hexatic intermediate. Our results demonstrate the merit of tomographic ultrafast structural probing in tracing coupled order parameters, heralding universal nanoscale access to laser-induced dimensionality control in functional heterostructures and devices.
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Affiliation(s)
- Till Domröse
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Thomas Danz
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sophie F Schaible
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany
| | - Kai Rossnagel
- Institute of Experimental and Applied Physics, Kiel University, Kiel, Germany
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - Sergey V Yalunin
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Claus Ropers
- Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
- 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany.
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9
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Iwasaki Y, Akase Z, Shimada K, Harada K, Shindo D. Time-resolved electron holography and its application to an ionic liquid specimen. Microscopy (Oxf) 2023; 72:455-459. [PMID: 36629509 PMCID: PMC10561666 DOI: 10.1093/jmicro/dfad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/29/2022] [Accepted: 01/10/2023] [Indexed: 01/12/2023] Open
Abstract
Time-resolved electron holography was implemented in a transmission electron microscope by means of electron beam gating with a parallel-plate electrostatic deflector. Stroboscopic observations were performed by accumulating gated electron interference images while applying a periodic modulation voltage to a specimen. Electric polarization in an ionic liquid specimen was observed under applied fields. While a static electric field in the specimen was reduced by the polarization of the material, an applied field modulated at 10 kHz was not screened. This indicates that time-resolved electron holography is capable of determining the frequency limit of dynamic response of polarization in materials. Graphical Abstract.
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Affiliation(s)
- Yoh Iwasaki
- Center for Emergent Matter Science, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Zentaro Akase
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Keiko Shimada
- Center for Emergent Matter Science, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Ken Harada
- Center for Emergent Matter Science, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Daisuke Shindo
- Center for Emergent Matter Science, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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10
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Yannai M, Adiv Y, Dahan R, Wang K, Gorlach A, Rivera N, Fishman T, Krüger M, Kaminer I. Lossless Monochromator in an Ultrafast Electron Microscope Using Near-Field THz Radiation. PHYSICAL REVIEW LETTERS 2023; 131:145002. [PMID: 37862634 DOI: 10.1103/physrevlett.131.145002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/03/2023] [Accepted: 08/21/2023] [Indexed: 10/22/2023]
Abstract
The ability to form monoenergetic electron beams is vital for high-resolution electron spectroscopy and imaging. Such capabilities are commonly achieved using an electron monochromator, which energy filters a dispersed electron beam, thus reducing the electron flux to yield down to meV energy resolution. This reduction in flux hinders the use of monochromators in many applications, such as ultrafast transmission electron microscopes (UTEMs). Here, we develop and demonstrate a mechanism for electron energy monochromation that does not reduce the flux-a lossless monochromator. The mechanism is based on the interaction of free-electron pulses with single-cycle THz near fields, created by nonlinear conversion of an optical laser pulse near the electron beam path inside a UTEM. Our experiment reduces the electron energy spread by a factor of up to 2.9 without compromising the beam flux. Moreover, as the electron-THz interaction takes place over an extended region of many tens of microns in free space, the realized technique is highly robust-granting uniform monochromation over a wide area, larger than the electron beam diameter. We further demonstrate the wide tunability of our method by monochromating the electron beam at multiple primary electron energies from 60 to 200 keV, studying the effect of various electron and THz parameters on its performance. Our findings have direct applications in the fast-growing field of ultrafast electron microscopy, allowing time- and energy-resolved studies of exciton physics, phononic vibrational resonances, charge transport effects, and optical excitations in the mid IR to the far IR.
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Affiliation(s)
- Michael Yannai
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yuval Adiv
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Raphael Dahan
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Kangpeng Wang
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201815, China
| | - Alexey Gorlach
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Nicholas Rivera
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Tal Fishman
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Michael Krüger
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Department of Physics, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ido Kaminer
- Faculty of Electrical & Computer Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- Solid State Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
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11
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Paschen T, Brückner L, Wu M, Spiecker E, Hommelhoff P. Highly Localized Optical Field Enhancement at Neon Ion Sputtered Tungsten Nanotips. NANO LETTERS 2023; 23:7114-7119. [PMID: 37470781 DOI: 10.1021/acs.nanolett.3c01985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
We present laser-driven rescattering of electrons at a nanometric protrusion (nanotip), which is fabricated with an in situ neon ion sputtering technique applied to a tungsten needle tip. Electron energy spectra obtained before and after the sputtering show rescattering features, such as a plateau and high-energy cutoff. Extracting the optical near-field enhancement in both cases, we observe a strong increase of more than 2-fold for the nanotip. Accompanying finite-difference time-domain (FDTD) simulations show a good match with the experimentally extracted near-field strengths. Additionally, high electric field localization for the nanotip is found. The combination of transmission electron microscope imaging of such nanotips and the determination of the near-field enhancement by electron rescattering represent a full characterization of the electric near-field of these intriguing electron emitters. Ultimately, nanotips as small as single nanometers can be produced, which is of utmost interest for electron diffraction experiments and low-emittance electron sources.
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Affiliation(s)
- Timo Paschen
- Department of Physics, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Leon Brückner
- Department of Physics, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Mingjian Wu
- Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Erdmann Spiecker
- Department of Materials Science and Engineering, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Peter Hommelhoff
- Department of Physics, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
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12
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Willis SA, Flannigan DJ. Stable Photoemission from the Wehnelt Aperture Surface in 4D Ultrafast Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1842-1844. [PMID: 37612902 DOI: 10.1093/micmic/ozad067.1103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Simon A Willis
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, United States
- Minnesota Institute of Ultrafast Science, University of Minnesota, Minneapolis, MN, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, United States
- Minnesota Institute of Ultrafast Science, University of Minnesota, Minneapolis, MN, United States
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13
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Flannigan DJ, VandenBussche EJ. Pulsed-beam transmission electron microscopy and radiation damage. Micron 2023; 172:103501. [PMID: 37390662 DOI: 10.1016/j.micron.2023.103501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/02/2023]
Abstract
We review the use of pulsed electron-beams in transmission electron microscopes (TEMs) for the purpose of mitigating specimen damage. We begin by placing the importance of TEMs with respect to materials characterization into proper context, and we provide a brief overview of established methods for reducing or eliminating the deleterious effects of beam-induced damage. We then introduce the concept of pulsed-beam TEM, and we briefly describe the basic methods and instrument configurations used to create so-called temporally structured electron beams. Following a brief overview of the use of high-dose-rate pulsed-electron beams in cancer radiation therapy, we review historical speculations and more recent compelling but mostly anecdotal findings of a pulsed-beam TEM damage effect. This is followed by an in-depth technical review of recent works seeking to establish cause-and-effect relationships, to conclusively uncover the presence of an effect, and to explore the practicality of the approach. These studies, in particular, provide the most compelling evidence to date that using a pulsed electron beam in the TEM is indeed a viable way to mitigate damage. Throughout, we point out current gaps in understanding, and we conclude with a brief perspective of current needs and future directions.
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Affiliation(s)
- David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA; Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Elisah J VandenBussche
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA; Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
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14
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Bhorade O, Deconihout B, Blum I, Moldovan S, Houard J, Normand A, Jagtap K, More M, Vella A. Bright and ultrafast electron point source made of LaB 6 nanotip. NANOSCALE ADVANCES 2023; 5:2462-2469. [PMID: 37143806 PMCID: PMC10153084 DOI: 10.1039/d3na00069a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/10/2023] [Indexed: 05/06/2023]
Abstract
The development of time-resolved transmission electron microscopy (TEM), ultrafast electron spectroscopy and pulsed X-ray sources relies on the realization of stable and high brightness sources of ultra-short electron bunches with a long service time. The flat photocathodes implanted in thermionic electron guns have been replaced by Schottky-type or cold-field emission sources driven by ultra-fast laser. Recently, lanthanum hexaboride (LaB6) nanoneedles have been reported to have high brightness and high emission stability when working in a continuous emission mode. Here, we prepare nano-field emitters from bulk LaB6 and we report on their use as ultra-fast electron sources. Using a high repetition rate laser in the infrared range, we present different field emission regimes as a function of the extraction voltage and laser intensity. The properties of the electron source (brightness, stability, energy spectrum and emission pattern) are determined for the different regimes. Our results show that LaB6 nanoneedles can be used as ultrafast and ultra-bright sources for time-resolved TEM, with better performances as compared to metallic ultra-fast field-emitters.
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Affiliation(s)
- O Bhorade
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - B Deconihout
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - I Blum
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - S Moldovan
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - J Houard
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - A Normand
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
| | - K Jagtap
- Department of Physics, Savitribai Phule Pune University Pune 411007 India
| | - M More
- Department of Physics, Savitribai Phule Pune University Pune 411007 India
| | - A Vella
- Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux Avenue de l'Université BP 12 76801 Saint Etienne du Rouvray France +33 232 955054 +33 232 955168
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15
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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: 5] [Impact Index Per Article: 5.0] [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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16
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Adhikari BC, Ketan B, Kim JS, Yoo ST, Choi EH, Park KC. Beam Trajectory Analysis of Vertically Aligned Carbon Nanotube Emitters with a Microchannel Plate. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4313. [PMID: 36500936 PMCID: PMC9738669 DOI: 10.3390/nano12234313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Vertically aligned carbon nanotubes (CNTs) are essential to studying high current density, low dispersion, and high brightness. Vertically aligned 14 × 14 CNT emitters are fabricated as an island by sputter coating, photolithography, and the plasma-enhanced chemical vapor deposition process. Scanning electron microscopy is used to analyze the morphology structures with an average height of 40 µm. The field emission microscopy image is captured on the microchannel plate (MCP). The role of the microchannel plate is to determine how the high-density electron beam spot is measured under the variation of voltage and exposure time. The MCP enhances the field emission current near the threshold voltage and protects the CNT from irreversible damage during the vacuum arc. The high-density electron beam spot is measured with an FWHM of 2.71 mm under the variation of the applied voltage and the exposure time, respectively, which corresponds to the real beam spot. This configuration produces the beam trajectory with low dispersion under the proper field emission, which could be applicable to high-resolution multi-beam electron microscopy and high-resolution X-ray imaging technology.
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Affiliation(s)
- Bishwa Chandra Adhikari
- Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 02447, Republic of Korea
| | - Bhotkar Ketan
- Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 02447, Republic of Korea
| | - Ju Sung Kim
- Department of Electrical and Biological Physics, Plasma Bioscience Research Center (PBRC), Kwangwoon University, Seoul 01897, Republic of Korea
| | - Sung Tae Yoo
- Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 02447, Republic of Korea
| | - Eun Ha Choi
- Department of Electrical and Biological Physics, Plasma Bioscience Research Center (PBRC), Kwangwoon University, Seoul 01897, Republic of Korea
| | - Kyu Chang Park
- Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 02447, Republic of Korea
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17
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Varkentina N, Auad Y, Woo SY, Zobelli A, Bocher L, Blazit JD, Li X, Tencé M, Watanabe K, Taniguchi T, Stéphan O, Kociak M, Tizei LHG. Cathodoluminescence excitation spectroscopy: Nanoscale imaging of excitation pathways. SCIENCE ADVANCES 2022; 8:eabq4947. [PMID: 36206335 PMCID: PMC9544325 DOI: 10.1126/sciadv.abq4947] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Following optical excitations' life span from creation to decay into photons is crucial in understanding materials photophysics. Macroscopically, this is studied using optical techniques, such as photoluminescence excitation spectroscopy. However, excitation and emission pathways can vary at nanometer scales, preventing direct access, as no characterization technique has the relevant spatial, spectral, and time resolution. Here, using combined electron spectroscopies, we explore excitations' creation and decay in two representative optical materials: plasmonic nanoparticles and luminescent two-dimensional layers. The analysis of the energy lost by an exciting electron that is coincident in time with a visible-ultraviolet photon unveils the decay pathways from excitation toward light emission. This is demonstrated for phase-locked (coherent) interactions (localized surface plasmons) and non-phase-locked ones (point defect excited states). The developed cathodoluminescence excitation spectroscopy images energy transfer pathways at the nanometer scale, widening the available toolset to explore nanoscale materials.
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Affiliation(s)
- Nadezda Varkentina
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Yves Auad
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Steffi Y. Woo
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Alberto Zobelli
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Laura Bocher
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Jean-Denis Blazit
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Xiaoyan Li
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Marcel Tencé
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Odile Stéphan
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Mathieu Kociak
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
| | - Luiz H. G. Tizei
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France
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18
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Curtis WA, Willis SA, Flannigan DJ. Single-photoelectron collection efficiency in 4D ultrafast electron microscopy. Phys Chem Chem Phys 2022; 24:14044-14054. [PMID: 35640169 DOI: 10.1039/d2cp01250b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In femtosecond (fs) 4D ultrafast electron microscopy (UEM), a tradeoff is made between photoelectrons per packet and time resolution. One consequence of this can be longer-than-desirable acquisition times for low-density packets, and particularly for low repetition rates when complete photothermal dissipation is required. Thus, gaining an understanding of photoelectron trajectories in the gun region is important for identifying factors that limit collection efficiency (CE; fraction of photoelectrons that enter the illumination system). Here, we continue our work on the systematic study of photoelectron trajectories in the gun region of a Thermo Fisher/FEI Tecnai Femto UEM, focusing specifically on CE in the single-electron regime. Using General Particle Tracer, calculated field maps, and the exact architecture of the Tecnai Femto UEM, we simulated the effects of fs laser parameters and key gun elements on CE. The results indicate CE strongly depends upon the laser spot size on the source, the (unbiased) Wehnelt aperture diameter, and the incident photon energy. The CE dispersion with laser spot size is found to be strongly dependent on aperture diameter, being nearly dispersionless for the largest apertures. A gun crossover is also observed, with the beam-waist position being dependent on the aperture diameter, further illustrating that the Wehnelt aperture acts as a simple, fixed electrostatic lens in UEM mode. This work provides further insights into the operational aspects of fs 4D UEM.
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Affiliation(s)
- Wyatt A Curtis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Simon A Willis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
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19
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Yakunin AN, Avetisyan YA, Akchurin GG, Zarkov SV, Aban’shin NP, Khanadeev VA, Tuchin VV. Photoemission of Plasmonic Gold Nanostars in Laser-Controlled Electron Current Devices for Technical and Biomedical Applications. SENSORS 2022; 22:s22114127. [PMID: 35684746 PMCID: PMC9185440 DOI: 10.3390/s22114127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 01/27/2023]
Abstract
The main goal of this work was to modify the previously developed blade-type planar structure using plasmonic gold nanostars in order to stimulate photofield emission and provide efficient laser control of the electron current. Localization and enhancement of the field at the tips of gold nanostars provided a significant increase in the tunneling electron current in the experimental sample (both electrical field and photofield emission). Irradiation at a wavelength in the vicinity of the plasmon resonance (red laser) provided a gain in the photoresponse value of up to 5 times compared to irradiation far from the resonance (green laser). The prospects for transition to regimes of structure irradiation by femtosecond laser pulses at the wavelength of surface plasmon resonance, which lead to an increase in the local optical field, are discussed. The kinetics of the energy density of photoinduced hot and thermalized electrons is estimated. The proposed laser-controlled matrix current source is promising for use in X-ray computed tomography systems.
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Affiliation(s)
- Alexander N. Yakunin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Correspondence: ; Tel.: +7-845-222-2376
| | - Yury A. Avetisyan
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
| | - Garif G. Akchurin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Science Medical Center, Saratov State University, 410012 Saratov, Russia
| | - Sergey V. Zarkov
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
| | | | - Vitaly A. Khanadeev
- Institute of Biochemistry and Physiology of Plants and Microorganisms, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410049 Saratov, Russia;
- Department of Microbiology, Biotechnology and Chemistry, Saratov State Agrarian University, 410012 Saratov, Russia
| | - Valery V. Tuchin
- Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the Russian Academy of Sciences”, 410028 Saratov, Russia; (Y.A.A.); (G.G.A.); (S.V.Z.); (V.V.T.)
- Science Medical Center, Saratov State University, 410012 Saratov, Russia
- Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, 634050 Tomsk, Russia
- Bach Institute of Biochemistry, FRC “Fundamentals of Biotechnology of the Russian Academy of Sciences”, 119071 Moscow, Russia
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20
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Ultrafast plasmonic photoemission in the single-cycle and few-cycle regimes. Sci Rep 2022; 12:3932. [PMID: 35273213 PMCID: PMC8913738 DOI: 10.1038/s41598-022-07259-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/15/2022] [Indexed: 11/29/2022] Open
Abstract
Due to the highly increased interest in the development of state-of-the-art applications of photoemission in ultrafast electron microscopy, development of photocathodes and many more applications, a correct theoretical understanding of the underlying phenomena is needed. Within the framework of the single active electron approximation the most accurate results can be obtained by the direct solution of the time-dependent Schrödinger equation (TDSE). In this work, after a brief presentation of a numerically improved version of a mixed 1D-TDSE method, we investigated the characteristics of electron spectra obtained from the surface of metal nanoparticles irradiated with ultrashort laser pulses. During our investigation different decay lengths of the plasmonic-enhanced incident field in the vicinity of the metal were considered. Using the simulated spectra we managed to identify the behavior of the cutoff energy as a function of decay length in the strong-field, multiphoton and transition regimes.
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21
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Li WH, Duncan CJR, Andorf MB, Bartnik AC, Bianco E, Cultrera L, Galdi A, Gordon M, Kaemingk M, Pennington CA, Kourkoutis LF, Bazarov IV, Maxson JM. A kiloelectron-volt ultrafast electron micro-diffraction apparatus using low emittance semiconductor photocathodes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2022; 9:024302. [PMID: 35350376 PMCID: PMC8934190 DOI: 10.1063/4.0000138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/16/2022] [Indexed: 06/12/2023]
Abstract
We report the design and performance of a time-resolved electron diffraction apparatus capable of producing intense bunches with simultaneously single digit micrometer probe size, long coherence length, and 200 fs rms time resolution. We measure the 5d (peak) beam brightness at the sample location in micro-diffraction mode to be 7 × 10 13 A / m 2 rad 2 . To generate high brightness electron bunches, the system employs high efficiency, low emittance semiconductor photocathodes driven with a wavelength near the photoemission threshold at a repetition rate up to 250 kHz. We characterize spatial, temporal, and reciprocal space resolution of the apparatus. We perform proof-of-principle measurements of ultrafast heating in single crystal Au samples and compare experimental results with simulations that account for the effects of multiple scattering.
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Affiliation(s)
- W. H. Li
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - C. J. R. Duncan
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - M. B. Andorf
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - A. C. Bartnik
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - E. Bianco
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - L. Cultrera
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - A. Galdi
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - M. Gordon
- University of Chicago, Chicago, Illinois 60637, USA
| | - M. Kaemingk
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - C. A. Pennington
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | | | - I. V. Bazarov
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - J. M. Maxson
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
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22
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Henke JW, Raja AS, Feist A, Huang G, Arend G, Yang Y, Kappert FJ, Wang RN, Möller M, Pan J, Liu J, Kfir O, Ropers C, Kippenberg TJ. Integrated photonics enables continuous-beam electron phase modulation. Nature 2021; 600:653-658. [PMID: 34937900 PMCID: PMC8695378 DOI: 10.1038/s41586-021-04197-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 11/01/2021] [Indexed: 11/10/2022]
Abstract
Integrated photonics facilitates extensive control over fundamental light-matter interactions in manifold quantum systems including atoms1, trapped ions2,3, quantum dots4 and defect centres5. Ultrafast electron microscopy has recently made free-electron beams the subject of laser-based quantum manipulation and characterization6-11, enabling the observation of free-electron quantum walks12-14, attosecond electron pulses10,15-17 and holographic electromagnetic imaging18. Chip-based photonics19,20 promises unique applications in nanoscale quantum control and sensing but remains to be realized in electron microscopy. Here we merge integrated photonics with electron microscopy, demonstrating coherent phase modulation of a continuous electron beam using a silicon nitride microresonator. The high-finesse (Q0 ≈ 106) cavity enhancement and a waveguide designed for phase matching lead to efficient electron-light scattering at extremely low, continuous-wave optical powers. Specifically, we fully deplete the initial electron state at a cavity-coupled power of only 5.35 microwatts and generate >500 electron energy sidebands for several milliwatts. Moreover, we probe unidirectional intracavity fields with microelectronvolt resolution in electron-energy-gain spectroscopy21. The fibre-coupled photonic structures feature single-optical-mode electron-light interaction with full control over the input and output light. This approach establishes a versatile and highly efficient framework for enhanced electron beam control in the context of laser phase plates22, beam modulators and continuous-wave attosecond pulse trains23, resonantly enhanced spectroscopy24-26 and dielectric laser acceleration19,20,27. Our work introduces a universal platform for exploring free-electron quantum optics28-31, with potential future developments in strong coupling, local quantum probing and electron-photon entanglement.
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Affiliation(s)
- Jan-Wilke Henke
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Arslan Sajid Raja
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Armin Feist
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Guanhao Huang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Germaine Arend
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Yujia Yang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - F Jasmin Kappert
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Rui Ning Wang
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Marcel Möller
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Jiahe Pan
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Junqiu Liu
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Ofer Kfir
- Georg-August-Universität Göttingen, Göttingen, Germany
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
| | - Claus Ropers
- Georg-August-Universität Göttingen, Göttingen, Germany.
- Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany.
| | - Tobias J Kippenberg
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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23
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Studying bacterial chemosensory array with CryoEM. Biochem Soc Trans 2021; 49:2081-2089. [PMID: 34495335 PMCID: PMC8589424 DOI: 10.1042/bst20210080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/16/2021] [Accepted: 08/19/2021] [Indexed: 12/30/2022]
Abstract
Bacteria direct their movement in respond to gradients of nutrients and other stimuli in the environment through the chemosensory system. The behavior is mediated by chemosensory arrays that are made up of thousands of proteins to form an organized array near the cell pole. In this review, we briefly introduce the architecture and function of the chemosensory array and its core signaling unit. We describe the in vivo and in vitro systems that have been used for structural studies of chemosensory array by cryoEM, including reconstituted lipid nanodiscs, 2D lipid monolayer arrays, lysed bacterial ghosts, bacterial minicells and native bacteria cells. Lastly, we review recent advances in structural analysis of chemosensory arrays using state-of-the-art cryoEM and cryoET methodologies, focusing on the latest developments and insights with a perspective on current challenges and future directions.
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24
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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] [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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Weber SJ. PyMoDAQ: An open-source Python-based software for modular data acquisition. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:045104. [PMID: 34243448 DOI: 10.1063/5.0032116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 03/27/2021] [Indexed: 06/13/2023]
Abstract
Thanks to the recent multiplication of scientific Python packages in the open-source software landscape, Data Acquisition frameworks (DAQ-Fs) appear as versatile replacements of custom-made or costly commercial solutions. PyMoDAQ is a DAQ-F focusing on easy-to-use graphical user interfaces allowing a simple control and automation of a large variety of experimental setups. Its development included a highly modular structure allowing any experimental data acquisition as a function of multiple varying parameters. It offers numerous additional functionalities: instrument and setup configuration, plotting, saving, logging, etc. Live visual feedback is available at all times to monitor the ongoing experiment. Flexibility of its user interfaces is the key advantage of PyMoDAQ allowing also its integration as the core of more focused applications. Its hierarchical binary format data saving mechanism includes experimental metadata highly compatible with FAIR (Findable, Accessible,Interoperable, Reusable) data. Among the presented characteristics, seven criteria have been chosen to judge the pertinence of PyMoDAQ as a versatile DAQ-F. They are also the basis for a comparison with other existing frameworks highlighting the novelty of PyMoDAQ.
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Affiliation(s)
- S J Weber
- CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, 31055 Toulouse, France
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Nanoscale-femtosecond dielectric response of Mott insulators captured by two-color near-field ultrafast electron microscopy. Nat Commun 2020; 11:5770. [PMID: 33188192 PMCID: PMC7666229 DOI: 10.1038/s41467-020-19636-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/26/2020] [Indexed: 11/09/2022] Open
Abstract
Characterizing and controlling the out-of-equilibrium state of nanostructured Mott insulators hold great promises for emerging quantum technologies while providing an exciting playground for investigating fundamental physics of strongly-correlated systems. Here, we use two-color near-field ultrafast electron microscopy to photo-induce the insulator-to-metal transition in a single VO2 nanowire and probe the ensuing electronic dynamics with combined nanometer-femtosecond resolution (10−21 m ∙ s). We take advantage of a femtosecond temporal gating of the electron pulse mediated by an infrared laser pulse, and exploit the sensitivity of inelastic electron-light scattering to changes in the material dielectric function. By spatially mapping the near-field dynamics of an individual nanowire of VO2, we observe that ultrafast photo-doping drives the system into a metallic state on a timescale of ~150 fs without yet perturbing the crystalline lattice. Due to the high versatility and sensitivity of the electron probe, our method would allow capturing the electronic dynamics of a wide range of nanoscale materials with ultimate spatiotemporal resolution. The fs control of an insulator-to-metal transition down to a few nanometers and its real-time/real space observation remain a challenge. Here, the authors demonstrate a method based on ultrafast electron microscopy to provide a nm/fs resolved view of the electronic dynamics in a single VO2 nanowire.
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Olshin PK, Drabbels M, Lorenz UJ. Characterization of a time-resolved electron microscope with a Schottky field emission gun. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:054304. [PMID: 33062804 PMCID: PMC7532021 DOI: 10.1063/4.0000034] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/07/2020] [Indexed: 05/27/2023]
Abstract
The rapid growth of the field of time-resolved and ultrafast electron microscopy has been accompanied by the active development of new instrumentation. Recently, time-resolved microscopes equipped with a field emission gun have been introduced, demonstrating great potential for experiments that benefit from the high brightness and coherence of the electron source. Here, we describe a straightforward design of a time-resolved transmission electron microscope with a Schottky field emission gun and characterize its performance. At the same time, our design gives us the flexibility to alternatively operate the instrument as if it was equipped with a flat metal photocathode. We can, thus, effectively choose to sacrifice brightness in order to obtain pulses with vastly larger numbers of electrons than from the emitter if for a given application the number of electrons is a crucial figure of merit. We believe that our straightforward and flexible design will be of great practical relevance to researchers wishing to enter the field.
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Abstract
Time-resolved electron microscopy is based on the excitation of a sample by pulsed laser radiation and its probing by synchronized photoelectron bunches in the electron microscope column. With femtosecond lasers, if probing pulses with a small number of electrons—in the limit, single-electron wave packets—are used, the stroboscopic regime enables ultrahigh spatiotemporal resolution to be obtained, which is not restricted by the Coulomb repulsion of electrons. This review article presents the current state of the ultrafast electron microscopy (UEM) method for detecting the structural dynamics of matter in the time range from picoseconds to attoseconds. Moreover, in the imaging mode, the spatial resolution lies, at best, in the subnanometer range, which limits the range of observation of structural changes in the sample. The ultrafast electron diffraction (UED), which created the methodological basis for the development of UEM, has opened the possibility of creating molecular movies that show the behavior of the investigated quantum system in the space-time continuum with details of sub-Å spatial resolution. Therefore, this review on the development of UEM begins with a description of the main achievements of UED, which formed the basis for the creation and further development of the UEM method. A number of recent experiments are presented to illustrate the potential of the UEM method.
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Paterson GW, Lamb RJ, Ballabriga R, Maneuski D, O'Shea V, McGrouther D. Sub-100 nanosecond temporally resolved imaging with the Medipix3 direct electron detector. Ultramicroscopy 2019; 210:112917. [PMID: 31841837 DOI: 10.1016/j.ultramic.2019.112917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/13/2019] [Accepted: 12/03/2019] [Indexed: 11/17/2022]
Abstract
Detector developments are currently enabling new capabilities in the field of transmission electron microscopy (TEM). We have investigated the limits of a hybrid pixel detector, Medipix3, to record dynamic, time varying, electron signals. Operating with an energy of 60 keV, we have utilised electrostatic deflection to oscillate electron beam position on the detector. Adopting a pump-probe imaging strategy, we have demonstrated that temporal resolutions three orders of magnitude smaller than are available for typically used TEM imaging detectors are possible. Our experiments have shown that energy deposition of the primary electrons in the hybrid pixel detector limits the overall temporal resolution. Through adjustment of user specifiable thresholds or the use of charge summing mode, we have obtained images composed from summing 10,000s frames containing single electron events to achieve temporal resolution less than 100 ns. We propose that this capability can be directly applied to studying repeatable material dynamic processes but also to implement low-dose imaging schemes in scanning transmission electron microscopy.
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Affiliation(s)
- Gary W Paterson
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
| | - Raymond J Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
| | | | - Dima Maneuski
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Val O'Shea
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Damien McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
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30
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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: 14] [Impact Index Per Article: 2.8] [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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31
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Tafel A, Meier S, Ristein J, Hommelhoff P. Femtosecond Laser-Induced Electron Emission from Nanodiamond-Coated Tungsten Needle Tips. PHYSICAL REVIEW LETTERS 2019; 123:146802. [PMID: 31702221 DOI: 10.1103/physrevlett.123.146802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/19/2019] [Indexed: 06/10/2023]
Abstract
We present femtosecond laser-induced electron emission from nanodiamond-coated tungsten tips. Based on the shortness of the femtosecond laser pulses, electrons can be photoexcited for wavelengths from the infrared (1932 nm) to the ultraviolet (235 nm) because multiphoton excitation becomes efficient over the entire spectral range. Depending on the laser wavelength, we find different dominant emission channels identified by the number of photons needed to emit electrons. Based on the band alignment between tungsten and nanodiamond, the relevant emission channels can be identified as specific transitions in diamond and its graphitic boundaries. It is the combination of the character of initial and final states (i.e., bulk or surface-near, direct or indirect excitation in the diamond band structure), the number of photons providing the excitation energy, and the peak intensity of the laser pulses that determines the dominant excitation channel for photoemission. A specific feature of the hydrogen-terminated nanodiamond coating is its negative electron affinity that significantly lowers the work function and enables efficient emission from the conduction band minimum into vacuum without an energy barrier. Emission is stable for bunch charges of up to 400 electrons per laser pulse. We infer a normalized emittance of <0.20 nm rad and a normalized peak brightness of >1.2×10^{12} A m^{-2} sr^{-1}. The properties of these tips are encouraging for their use as laser-triggered electron sources in applications such as ultrafast electron microscopy as well as diffraction and novel photonics-based laser accelerators.
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Affiliation(s)
- A Tafel
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 1, D-91058 Erlangen, Germany
| | - S Meier
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 1, D-91058 Erlangen, Germany
| | - J Ristein
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 1, D-91058 Erlangen, Germany
| | - P Hommelhoff
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 1, D-91058 Erlangen, Germany
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32
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VandenBussche EJ, Flannigan DJ. Reducing Radiation Damage in Soft Matter with Femtosecond-Timed Single-Electron Packets. NANO LETTERS 2019; 19:6687-6694. [PMID: 31433192 DOI: 10.1021/acs.nanolett.9b03074] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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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33
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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: 12] [Impact Index Per Article: 2.4] [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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34
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Madan I, Vanacore GM, Pomarico E, Berruto G, Lamb RJ, McGrouther D, Lummen TTA, Latychevskaia T, García de Abajo FJ, Carbone F. Holographic imaging of electromagnetic fields via electron-light quantum interference. SCIENCE ADVANCES 2019; 5:eaav8358. [PMID: 31058225 PMCID: PMC6499551 DOI: 10.1126/sciadv.aav8358] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/15/2019] [Indexed: 05/22/2023]
Abstract
Holography relies on the interference between a known reference and a signal of interest to reconstruct both the amplitude and the phase of that signal. With electrons, the extension of holography to the ultrafast time domain remains a challenge, although it would yield the highest possible combined spatiotemporal resolution. Here, we show that holograms of local electromagnetic fields can be obtained with combined attosecond/nanometer resolution in an ultrafast transmission electron microscope (UEM). Unlike conventional holography, where signal and reference are spatially separated and then recombined to interfere, our method relies on electromagnetic fields to split an electron wave function in a quantum coherent superposition of different energy states. In the image plane, spatial modulation of the electron energy distribution reflects the phase relation between reference and signal fields. Beyond imaging applications, this approach allows implementing quantum measurements in parallel, providing an efficient and versatile tool for electron quantum optics.
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Affiliation(s)
- I. Madan
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - G. M. Vanacore
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - E. Pomarico
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - G. Berruto
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - R. J. Lamb
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - D. McGrouther
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - T. T. A. Lummen
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - T. Latychevskaia
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
| | - F. J. 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
| | - F. Carbone
- Institute of Physics, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
- Corresponding author.
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35
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Borz M, Mammez MH, Blum I, Houard J, Da Costa G, Delaroche F, Idlahcen S, Haboucha A, Hideur A, Kleshch VI, Obraztsov AN, Vella A. Photoassisted and multiphoton emission from single-crystal diamond needles. NANOSCALE 2019; 11:6852-6858. [PMID: 30912570 DOI: 10.1039/c9nr01001g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Practical realization of stable and high brightness sources of ultra-short electron pulses is an important issue in the development of time-resolved electron microscopy for the study of ultra-fast dynamics in materials. Here, we report on the experimental investigation of static (in the dark) and pulsed (under illumination by sub-picosecond laser pulses at 1040 nm) electron emission from single-crystal diamond needles. A significant increase of electron emission current was detected under laser illumination. The nonlinear dependence of the emission current on the laser intensity and on the angle between the needle and the laser beam polarization axis suggests multi-photon emission processes. This interpretation is in agreement with electron spectroscopy measurements performed for electrons emitted at different bias voltages and different laser power levels and repetition rates. The remarkable feature of the diamond emitters is their stability under high average power of laser radiation. This provides a new highly efficient source of photoemitted electrons based on single-crystal diamond.
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Affiliation(s)
- M Borz
- Groupe de Physique des Matériaux UMR CNRS 6634, Normandie Université, Université-INSA de Rouen, Avenue de l'Université BP 12, 76801 Saint Etienne du Rouvray, France.
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36
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Turchetti M, Kim CS, Hobbs R, Yang Y, Kruit P, Berggren KK. Design and simulation of a linear electron cavity for quantum electron microscopy. Ultramicroscopy 2019; 199:50-61. [PMID: 30772718 DOI: 10.1016/j.ultramic.2019.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 01/01/2019] [Accepted: 01/20/2019] [Indexed: 11/16/2022]
Abstract
Quantum electron microscopy (QEM) is a measurement approach that could reduce sample radiation damage, which represents the main obstacle to sub-nanometer direct imaging of molecules in conventional electron microscopes. This method is based on the exploitation of interaction-free measurements in an electron resonator. In this work, we present the design of a linear resonant electron cavity, which is at the core of QEM. We assess its stability and optical properties during resonance using ray-tracing electron optical simulations. Moreover, we analyze the issue of spherical aberrations inside the cavity and we propose and verify through simulation two possible approaches to the problem. Finally, we discuss some of the important design parameters and constraints, such as conservation of temporal coherence and effect of alignment fields.
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Affiliation(s)
- Marco Turchetti
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Chung-Soo Kim
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Richard Hobbs
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yujia Yang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Pieter Kruit
- Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, Netherlands
| | - Karl K Berggren
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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37
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Bach N, Domröse T, Feist A, Rittmann T, Strauch S, Ropers C, Schäfer S. Coulomb interactions in high-coherence femtosecond electron pulses from tip emitters. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:014301. [PMID: 30868085 PMCID: PMC6404915 DOI: 10.1063/1.5066093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/08/2019] [Indexed: 05/26/2023]
Abstract
Tip-based photoemission electron sources offer unique properties for ultrafast imaging, diffraction, and spectroscopy experiments with highly coherent few-electron pulses. Extending this approach to increased bunch-charges requires a comprehensive experimental study on Coulomb interactions in nanoscale electron pulses and their impact on beam quality. For a laser-driven Schottky field emitter, we assess the transverse and longitudinal electron pulse properties in an ultrafast transmission electron microscope at a high photoemission current density. A quantitative characterization of electron beam emittance, pulse duration, spectral bandwidth, and chirp is performed. Due to the cathode geometry, Coulomb interactions in the pulse predominantly occur in the direct vicinity to the tip apex, resulting in a well-defined pulse chirp and limited emittance growth. Strategies for optimizing electron source parameters are identified, enabling advanced ultrafast transmission electron microscopy approaches, such as phase-resolved imaging and holography.
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Affiliation(s)
- Nora Bach
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Till Domröse
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Armin Feist
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Thomas Rittmann
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Stefanie Strauch
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
| | - Claus Ropers
- 4th Physical Institute - Solids and Nanostructures, University of Goettingen, Goettingen, Germany
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38
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Stimulated electron energy loss and gain in an electron microscope without a pulsed electron gun. Ultramicroscopy 2018; 203:44-51. [PMID: 31000482 DOI: 10.1016/j.ultramic.2018.12.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/06/2018] [Accepted: 12/16/2018] [Indexed: 11/21/2022]
Abstract
We report on a novel way of performing stimulated electron energy-loss and energy-gain spectroscopy (sEELS/sEEGS) experiments that does not require a pulsed gun. In this scheme, a regular scanning transmission electron microscope (STEM) equipped with a conventional continuous electron gun is fitted with a modified EELS detector and a light injector in the object chamber. The modification of the EELS detector allows one to expose the EELS camera during tunable time intervals that can be synchronized with nanosecond laser pulses hitting the sample, therefore allowing us to collect only those electrons that have interacted with the sample under light irradiation. Using ∼ 5 ns laser pulses of ∼ 2 eV photon energy on various plasmonic silver samples, we obtain evidence of sEELS/sEEGS through the emergence of up to two loss and gain peaks in the spectra at ± 2 and ± 4 eV. Because this approach does not involve any modification of the gun, our method retains the original performances of the microscope in terms of energy resolution and spectral imaging with and without light injection. Compared to pulsed-gun techniques, our method is mainly limited to a perturbative regime (typically no more that one gain event per incident electron), which allows us to observe resonant effects, in particular when the plasmon energy of a silver nanostructure matches the laser photon energy. In this situation, EELS and EEGS signals are enhanced in proportion to n+1 and n, respectively, where n is the average plasmon population due to the external illumination. The n term is associated with stimulated loss and gain processes, and the term of 1 corresponds to conventional (spontaneous) loss. The EELS part of the spectrum is therefore an incoherent superposition of spontaneous and stimulated EEL events. This is confirmed by a proper quantum-mechanical description of the electron/light/plasmon system incorporating light-plasmon and plasmon-electron interactions, as well as inelastic plasmon decay.
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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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Barlow Myers CW, Pine NJ, Bryan WA. Femtosecond transmission electron microscopy for nanoscale photonics: a numerical study. NANOSCALE 2018; 10:20628-20639. [PMID: 30387797 DOI: 10.1039/c8nr06235h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recent developments in ultrafast electron microscopy have shown that spatial and temporal information can be collected simultaneously on very small and fast scales. In the present work, an instrumental design study with application to nanoscale dynamics, we optimize the conditions for a femtosecond transmission electron microscope (fs-TEM). The fs-TEM numerically studied employs a metallic nanotip source, electrostatic acceleration, magnetic lenses, a condenser-objective around the sample and a temporal compressor, and considers space-charge effects during propagation. We find a spatial resolution of the order of 1 nm and a temporal resolution of below 10 fs will be feasible for pulses comprised of on average 20 electrons. The influence of a transverse electric field at the sample plane is modelled, indicating 1 V μm-1 can be resolved, corresponding to a surface charge density of 10e per μm2, comparable to fields generated in light-driven electronics and ultrafast nanoplasmonics. The realisation of such an instrument is anticipated to facilitate unprecedented elucidation of laser-initiated physical, chemical and biological structural dynamics on atomic time- and length-scales.
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Affiliation(s)
- C W Barlow Myers
- Department of Physics, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK.
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Ultrafast Transmission Electron Microscopy: Historical Development, Instrumentation, and Applications. ADVANCES IN IMAGING AND ELECTRON PHYSICS 2018. [DOI: 10.1016/bs.aiep.2018.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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