1
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Lee C, Kassier GH, Miller RJD. High bunch charge low-energy electron streak diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:024309. [PMID: 38595978 PMCID: PMC11003762 DOI: 10.1063/4.0000246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 03/07/2024] [Indexed: 04/11/2024]
Abstract
For time-resolved diffraction studies of irreversible structural dynamics upon photoexcitation, there are constraints on the number of perturbation cycles due to thermal effects and accumulated strain, which impact the degree of crystal order and spatial resolution. This problem is exasperated for surface studies that are more prone to disordering and defect formation. Ultrafast electron diffraction studies of these systems, with the conventional stroboscopic pump-probe protocol, require repetitive measurements on well-prepared diffraction samples to acquire and average signals above background in the dynamic range of interest from few tens to hundreds of picoseconds. Here, we present ultrafast streaked low-energy electron diffraction (LEED) that demands, in principle, only a single excitation per nominal data acquisition timeframe. By exploiting the space-time correlation characteristics of the streaking method and high-charge 2 keV electron bunches in the transmission geometry, we demonstrate about one order of magnitude reduction in the accumulated number of the excitation cycles and total electron dose, and 48% decrease in the root mean square error of the model fit residual compared to the conventional time-scanning measurement. We believe that our results demonstrate a viable alternative method with higher sensitivity to that of nanotip-based ultrafast LEED studies relying on a few electrons per a single excitation, to access to all classes of structural dynamics to provide an atomic level view of surface processes.
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Affiliation(s)
- Chiwon Lee
- Departments of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Günther H. Kassier
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - R. J. Dwayne Miller
- Departments of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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2
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Li C, Guan M, Hong H, Chen K, Wang X, Ma H, Wang A, Li Z, Hu H, Xiao J, Dai J, Wan X, Liu K, Meng S, Dai Q. Coherent ultrafast photoemission from a single quantized state of a one-dimensional emitter. SCIENCE ADVANCES 2023; 9:eadf4170. [PMID: 37824625 PMCID: PMC10569710 DOI: 10.1126/sciadv.adf4170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 09/08/2023] [Indexed: 10/14/2023]
Abstract
Femtosecond laser-driven photoemission source provides an unprecedented femtosecond-resolved electron probe not only for atomic-scale ultrafast characterization but also for free-electron radiation sources. However, for conventional metallic electron source, intense lasers may induce a considerable broadening of emitting energy level, which results in large energy spread (>600 milli-electron volts) and thus limits the spatiotemporal resolution of electron probe. Here, we demonstrate the coherent ultrafast photoemission from a single quantized energy level of a carbon nanotube. Its one-dimensional body can provide a sharp quantized electronic excited state, while its zero-dimensional tip can provide a quantized energy level act as a narrow photoemission channel. Coherent resonant tunneling electron emission is evidenced by a negative differential resistance effect and a field-driven Stark splitting effect. The estimated energy spread is ~57 milli-electron volts, which suggests that the proposed carbon nanotube electron source may promote electron probe simultaneously with subangstrom spatial resolution and femtosecond temporal resolution.
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Affiliation(s)
- Chi Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Mengxue Guan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190, China
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (Ministry of Education), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Hao Hong
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Ke Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Xiaowei Wang
- Department of Physics, Hunan Key Laboratory of Extreme Matter and Applications, National University of Defense Technology, Changsha 410073, China
| | - He Ma
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Aiwei Wang
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Zhenjun Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Hai Hu
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Jianfeng Xiao
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Jiayu Dai
- Department of Physics, Hunan Key Laboratory of Extreme Matter and Applications, National University of Defense Technology, Changsha 410073, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190, China
| | - Qing Dai
- CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing 100190, China
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3
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Ebel S, Talebi N. Inelastic electron scattering at a single-beam structured light wave. COMMUNICATIONS PHYSICS 2023; 6:179. [PMID: 38665404 PMCID: PMC11041727 DOI: 10.1038/s42005-023-01300-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 07/06/2023] [Indexed: 04/28/2024]
Abstract
In free space, electrons undergo inelastic scattering in the presence of ponderomotive potentials generated by light pulses and standing light waves. The resulting modulated electron energy spectrum can exhibit the formation of discrete energy sidebands when multiple light beams are employed. Here, we demonstrate the inelastic scattering of slow-electron wavepackets at a propagating Hermite-Gaussian light beam. The pulsed Hermite-Gaussian beam thus forms a ponderomotive potential for the electron with sufficient momentum components, leading to the inelastic scattering and subsequent formation of discrete energy sidebands. We show that the resulting energy-gain spectra after the interaction are strongly influenced by the self-interference of the electrons in this ponderomotive potential. This effect is observable across various wavelengths, and the energy modulation can be controlled by varying the electron velocity and light intensity. By utilizing the vast landscape of structured electromagnetic fields, this effect introduces an additional platform for manipulating electron wavepackets.
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Affiliation(s)
- Sven Ebel
- Institute of Experimental and Applied Physics, Kiel University, Kiel, Germany
| | - Nahid Talebi
- Institute of Experimental and Applied Physics, Kiel University, Kiel, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Kiel, Germany
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4
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de Raadt TCH, Franssen JGH, Luiten OJ. Subpicosecond Ultracold Electron Source. PHYSICAL REVIEW LETTERS 2023; 130:205001. [PMID: 37267545 DOI: 10.1103/physrevlett.130.205001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 03/01/2023] [Accepted: 03/29/2023] [Indexed: 06/04/2023]
Abstract
We present the first observation of subpicosecond electron bunches from an ultracold electron source. This source is based on near-threshold, two-step, femtosecond photoionization of laser-cooled rubidium gas in a grating magneto-optical trap. Bunch lengths as short as 735±7 fs (rms) have been measured in the self-compression point of the source by means of ponderomotive scattering of the electrons by a 25 fs, 800 nm laser pulse. The observed temporal structure of the electron bunch depends on the central wavelength of the ionization laser pulse, in agreement with detailed simulations of the atomic photoionization process. This shows that the bunch length limit imposed by the atomic photoionization process has been reached.
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Affiliation(s)
- T C H de Raadt
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - J G H Franssen
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - O J Luiten
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
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5
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Johnson CW, Schmid AK, Mankos M, Röpke R, Kerker N, Wong EK, Ogletree DF, Minor AM, Stibor A. Near-Monochromatic Tuneable Cryogenic Niobium Electron Field Emitter. PHYSICAL REVIEW LETTERS 2022; 129:244802. [PMID: 36563244 DOI: 10.1103/physrevlett.129.244802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 09/29/2022] [Indexed: 06/17/2023]
Abstract
Creating, manipulating, and detecting coherent electrons is at the heart of future quantum microscopy and spectroscopy technologies. Leveraging and specifically altering the quantum features of an electron beam source at low temperatures can enhance its emission properties. Here, we describe electron field emission from a monocrystalline, superconducting niobium nanotip at a temperature of 5.9 K. The emitted electron energy spectrum reveals an ultranarrow distribution down to 16 meV due to tunable resonant tunneling field emission via localized band states at a nanoprotrusion's apex and a cutoff at the sharp low-temperature Fermi edge. This is an order of magnitude lower than for conventional field emission electron sources. The self-focusing geometry of the tip leads to emission in an angle of 3.7°, a reduced brightness of 3.8×10^{8} A/(m^{2} sr V), and a stability of hours at 4.1 nA beam current and 69 meV energy width. This source will decrease the impact of lens aberration and enable new modes in low-energy electron microscopy, electron energy loss spectroscopy, and high-resolution vibrational spectroscopy.
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Affiliation(s)
- C W Johnson
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
| | - A K Schmid
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
| | - M Mankos
- Electron Optica Inc., Palo Alto, California 94303, USA
| | - R Röpke
- Institute of Physics and LISA+, University of Tübingen, Tübingen 72076, Germany
| | - N Kerker
- Institute of Physics and LISA+, University of Tübingen, Tübingen 72076, Germany
| | - E K Wong
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
| | - D F Ogletree
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
| | - A M Minor
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - A Stibor
- Lawrence Berkeley National Lab, Molecular Foundry, Berkeley, California 94720, USA
- Electron Optica Inc., Palo Alto, California 94303, USA
- Institute of Physics and LISA+, University of Tübingen, Tübingen 72076, Germany
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6
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Jones LB, Juarez-Lopez DP, Scheibler HE, Terekhov AS, Militsyn BL, Welsch CP, Noakes TCQ. The measurement of photocathode transverse energy distribution curves (TEDCs) using the transverse energy spread spectrometer (TESS) experimental system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113314. [PMID: 36461497 DOI: 10.1063/5.0109053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/28/2022] [Indexed: 06/17/2023]
Abstract
The minimum achievable particle beam emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source. This is measurable as the mean longitudinal and transverse energy spreads in the photoemitted electron beam (MLE and MTE respectively); consequently, MLE and MTE are notable figures of merit for photocathodes used as electron sources in particle accelerators. The overall energy spread is defined by the sum of the MTE and the MLE, and the minimization of MTE is crucial to reduce emittance and thus generate a high-brightness electron beam. Reducing the electron beam emittance in an accelerator that drives a Free-Electron Laser (FEL) delivers a significant reduction in the saturation length for an x-ray FEL, thus reducing the machine's construction footprint and operating costs while increasing the x-ray beam brightness. The ability to measure the transverse energy distribution curve of photoelectrons emitted from a photocathode is a key enabler in photocathode research and development that has prompted the Accelerator Science and Technology Centre (ASTeC) at the STFC Daresbury Laboratory to develop the Transverse Energy Spread Spectrometer to make these crucial measurements. We present details of the design for the upgraded TESS instrument with measured data for copper (100), (110), and (111) single-crystal photocathodes illuminated at UV wavelengths around 266 nm.
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Affiliation(s)
- L B Jones
- ASTeC, STFC Daresbury Laboratory, WA4 4AD, Warrington, United Kingdom
| | - D P Juarez-Lopez
- Cockcroft Institute of Accelerator Science and Technology, WA4 4AD Warrington, United Kingdom
| | - H E Scheibler
- The Rhaznov Institute of Semiconductor Physics, SB RAS, Novosibirsk, Russia
| | - A S Terekhov
- The Rhaznov Institute of Semiconductor Physics, SB RAS, Novosibirsk, Russia
| | - B L Militsyn
- ASTeC, STFC Daresbury Laboratory, WA4 4AD, Warrington, United Kingdom
| | - C P Welsch
- Cockcroft Institute of Accelerator Science and Technology, WA4 4AD Warrington, United Kingdom
| | - T C Q Noakes
- ASTeC, STFC Daresbury Laboratory, WA4 4AD, Warrington, United Kingdom
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7
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Rusetsky VS, Golyashov VA, Eremeev SV, Kustov DA, Rusinov IP, Shamirzaev TS, Mironov AV, Demin AY, Tereshchenko OE. New Spin-Polarized Electron Source Based on Alkali Antimonide Photocathode. PHYSICAL REVIEW LETTERS 2022; 129:166802. [PMID: 36306756 DOI: 10.1103/physrevlett.129.166802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
New spin-dependent photoemission properties of alkali antimonide semiconductor cathodes are predicted based on the detected optical spin orientation effect and DFT band structure calculations. Using these results, the Na_{2}KSb/Cs_{3}Sb heterostructure is designed as a spin-polarized electron source in combination with the Al_{0.11}Ga_{0.89}As target as a spin detector with spatial resolution. In the Na_{2}KSb/Cs_{3}Sb photocathode, spin-dependent photoemission properties were established through detection of a high degree of photoluminescence polarization and high polarization of the photoemitted electrons. It was found that the multi-alkali photocathode can provide electron beams with emittance very close to the limits imposed by the electron thermal energy. The vacuum tablet-type sources of spin-polarized electrons have been proposed for accelerators, which can exclude the construction of the photocathode growth chambers for photoinjectors.
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Affiliation(s)
- V S Rusetsky
- Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia
- CJSC "Ekran FEP", Novosibirsk 630060, Russia
| | - V A Golyashov
- Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Synchrotron radiation facility SKIF, Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Kol'tsovo 630559, Russia
- Novosibirsk State University, Novosibirsk 630090 Russia
| | - S V Eremeev
- Institute of Strength Physics and Materials Science, Tomsk 634055, Russia
| | - D A Kustov
- Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - I P Rusinov
- Tomsk State University, Tomsk 634050, Russia
| | - T S Shamirzaev
- Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090 Russia
| | - A V Mironov
- CJSC "Ekran FEP", Novosibirsk 630060, Russia
| | - A Yu Demin
- CJSC "Ekran FEP", Novosibirsk 630060, Russia
| | - O E Tereshchenko
- Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Synchrotron radiation facility SKIF, Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Kol'tsovo 630559, Russia
- Novosibirsk State University, Novosibirsk 630090 Russia
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8
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Parzyck CT, Galdi A, Nangoi JK, DeBenedetti WJI, Balajka J, Faeth BD, Paik H, Hu C, Arias TA, Hines MA, Schlom DG, Shen KM, Maxson JM. Single-Crystal Alkali Antimonide Photocathodes: High Efficiency in the Ultrathin Limit. PHYSICAL REVIEW LETTERS 2022; 128:114801. [PMID: 35363005 DOI: 10.1103/physrevlett.128.114801] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
The properties of photoemission electron sources determine the ultimate performance of a wide class of electron accelerators and photon detectors. To date, all high-efficiency visible-light photocathode materials are either polycrystalline or exhibit intrinsic surface disorder, both of which limit emitted electron beam brightness. In this Letter, we demonstrate the synthesis of epitaxial thin films of Cs_{3}Sb on 3C-SiC (001) using molecular-beam epitaxy. Films as thin as 4 nm have quantum efficiencies exceeding 2% at 532 nm. We also find that epitaxial films have an order of magnitude larger quantum efficiency at 650 nm than comparable polycrystalline films on Si. Additionally, these films permit angle-resolved photoemission spectroscopy measurements of the electronic structure, which are found to be in good agreement with theory. Epitaxial films open the door to dramatic brightness enhancements via increased efficiency near threshold, reduced surface disorder, and the possibility of engineering new photoemission functionality at the level of single atomic layers.
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Affiliation(s)
- C T Parzyck
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - A Galdi
- Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA
| | - J K Nangoi
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - W J I DeBenedetti
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - J Balajka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - B D Faeth
- Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, New York 14853, USA
| | - H Paik
- Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, New York 14853, USA
| | - C Hu
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - T A Arias
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
| | - M A Hines
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - D G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, USA
- Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, Germany
| | - K M Shen
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, 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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9
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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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10
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Antoniuk ER, Schindler P, Schroeder WA, Dunham B, Pianetta P, Vecchione T, Reed EJ. Novel Ultrabright and Air-Stable Photocathodes Discovered from Machine Learning and Density Functional Theory Driven Screening. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104081. [PMID: 34510594 DOI: 10.1002/adma.202104081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/28/2021] [Indexed: 06/13/2023]
Abstract
The high brightness, low emittance electron beams achieved in modern X-ray free-electron lasers (XFELs) have enabled powerful X-ray imaging tools, allowing molecular systems to be imaged at picosecond time scales and sub-nanometer length scales. One of the most promising directions for increasing the brightness of XFELs is through the development of novel photocathode materials. Whereas past efforts aimed at discovering photocathode materials have typically employed trial-and-error-based iterative approaches, this work represents the first data-driven screening for high brightness photocathode materials. Through screening over 74 000 semiconducting materials, a vast photocathode dataset is generated, resulting in statistically meaningful insights into the nature of high brightness photocathode materials. This screening results in a diverse list of photocathode materials that exhibit intrinsic emittances that are up to 4x lower than currently used photocathodes. In a second effort, multiobjective screening is employed to identify the family of M2 O (M = Na, K, Rb) that exhibits photoemission properties that are comparable to the current state-of-the-art photocathode materials, but with superior air stability. This family represents perhaps the first intrinsically bright, visible light photocathode materials that are resistant to reactions with oxygen, allowing for their transport and storage in dry air environments.
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Affiliation(s)
- Evan R Antoniuk
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Peter Schindler
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Faculty of Physics, University of Vienna, Vienna, 1010, Austria
| | - W Andreas Schroeder
- Department of Physics, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | | | | | | | - Evan J Reed
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
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11
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Wang E, Litvinenko VN, Pinayev I, Gaowei M, Skaritka J, Belomestnykh S, Ben-Zvi I, Brutus JC, Jing Y, Biswas J, Ma J, Narayan G, Petrushina I, Rahman O, Xin T, Rao T, Severino F, Shih K, Smith K, Wang G, Wu Y. Long lifetime of bialkali photocathodes operating in high gradient superconducting radio frequency gun. Sci Rep 2021; 11:4477. [PMID: 33627743 PMCID: PMC7904862 DOI: 10.1038/s41598-021-83997-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 02/08/2021] [Indexed: 11/09/2022] Open
Abstract
High brightness, high charge electron beams are critical for a number of advanced accelerator applications. The initial emittance of the electron beam, which is determined by the mean transverse energy (MTE) and laser spot size, is one of the most important parameters determining the beam quality. The bialkali photocathodes illuminated by a visible laser have the advantages of high quantum efficiency (QE) and low MTE. Furthermore, Superconducting Radio Frequency (SRF) guns can operate in the continuous wave (CW) mode at high accelerating gradients, e.g. with significant reduction of the laser spot size at the photocathode. Combining the bialkali photocathode with the SRF gun enables generation of high charge, high brightness, and possibly high average current electron beams. However, integrating the high QE semiconductor photocathode into the SRF guns has been challenging. In this article, we report on the development of bialkali photocathodes for successful operation in the SRF gun with months-long lifetime while delivering CW beams with nano-coulomb charge per bunch. This achievement opens a new era for high charge, high brightness CW electron beams.
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Affiliation(s)
- E Wang
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - V N Litvinenko
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - I Pinayev
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Gaowei
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J Skaritka
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - S Belomestnykh
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA.,Fermi National Accelerator Laboratory, Batavia, IL, 60510, USA
| | - I Ben-Zvi
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - J C Brutus
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Y Jing
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - J Biswas
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - J Ma
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - G Narayan
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - I Petrushina
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - O Rahman
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - T Xin
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - T Rao
- Instrumentation Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - F Severino
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - K Shih
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - K Smith
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - G Wang
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Y Wu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
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