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Zhu C, Zheng D, Wang H, Zhang M, Li Z, Sun S, Xu P, Tian H, Li Z, Yang H, Li J. Development of analytical ultrafast transmission electron microscopy based on laser-driven Schottky field emission. Ultramicroscopy 2019; 209:112887. [PMID: 31739190 DOI: 10.1016/j.ultramic.2019.112887] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/29/2019] [Accepted: 11/09/2019] [Indexed: 10/25/2022]
Abstract
A new design scheme for ultrafast transmission electron microscopy (UTEM) has been developed based on a Schottky-type field emission gun (FEG) at the Institute of Physics, Chinese Academy of Sciences (IOP CAS). In this UTEM setup, electron pulse emission is achieved by integrating a laser port between the electron gun and the column and the resulting microscope can operate in either continuous or pulsed mode. In pulsed mode, the optimized electron beam properties are an energy width of ~0.65 eV, micrometer-scale coherence lengths and sub-picosecond pulse durations. The potential applications of this UTEM, which include electron diffraction, high-resolution imaging, electron energy loss spectroscopy, and photon-induced near-field electron microscopy, are demonstrated using ultrafast electron pulses. Furthermore, we use a nanosecond laser (~10 ns) to show that the laser-driven FEG can support high-quality TEM imaging and electron holography when using a stroboscopic configuration. Our results also indicate that FEG-based ultrafast electron sources may enable high-performance analytical UTEM.
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Affiliation(s)
- Chunhui Zhu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Dingguo Zheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Hong Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Ming Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhongwen Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shuaishuai Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Peng Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huanfang Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zian Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huaixin Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China; Yangtze River Delta Physics Research Center Co., Ltd., Liyang, Jiangsu, 213300, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jianqi Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China.
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Karkare S, Feng J, Chen X, Wan W, Palomares FJ, Chiang TC, Padmore HA. Reduction of Intrinsic Electron Emittance from Photocathodes Using Ordered Crystalline Surfaces. PHYSICAL REVIEW LETTERS 2017; 118:164802. [PMID: 28474903 DOI: 10.1103/physrevlett.118.164802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Indexed: 06/07/2023]
Abstract
The generation of intense electron beams with low emittance is key to both the production of coherent x rays from free electron lasers, and electron pulses with large transverse coherence length used in ultrafast electron diffraction. These beams are generated today by photoemission from disordered polycrystalline surfaces. We show that the use of single crystal surfaces with appropriate electronic structures allows us to effectively utilize the physics of photoemission to generate highly directed electron emission, thus reducing the emittance of the electron beam being generated.
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Affiliation(s)
- Siddharth Karkare
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA
| | - Jun Feng
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA
| | - Xumin Chen
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA
| | - Weishi Wan
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA
| | - F Javier Palomares
- Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz, 3, 28049 Madrid, Spain
| | - T-C Chiang
- Department of Physics, University of Illinois, Urbana, Illinois 61801 USA and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 USA
| | - Howard A Padmore
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, California 94720, USA
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Feng J, Nasiatka J, Wan W, Vecchione T, Padmore HA. A novel system for measurement of the transverse electron momentum distribution from photocathodes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:015103. [PMID: 25638118 DOI: 10.1063/1.4904930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/08/2014] [Indexed: 06/04/2023]
Abstract
The transverse momentum of electrons produced by a photocathode contributes significantly to the performance of several different types of accelerator-based light sources, such as Free Electron Lasers, as well as systems designed for ultrafast electron diffraction and dynamic transmission electron microscopy. Minimization of the transverse emittance from photocathodes is the subject of intensive research, and therefore measurement of this parameter is of great importance. Here, we describe a simple system that offers real time measurements of transverse emittance and can be easily integrated into the photocathode fabrication process.
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Affiliation(s)
- J Feng
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J Nasiatka
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - W Wan
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T Vecchione
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - H A Padmore
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Droubay TC, Chambers SA, Joly AG, Hess WP, Németh K, Harkay KC, Spentzouris L. Metal-insulator photocathode heterojunction for directed electron emission. PHYSICAL REVIEW LETTERS 2014; 112:067601. [PMID: 24580707 DOI: 10.1103/physrevlett.112.067601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 06/03/2023]
Abstract
We use angle-resolved photoemission under ultraviolet laser excitation to demonstrate that the electron emission properties of Ag(001) can be markedly enhanced and redirected along the surface normal by the deposition of a few monolayers of epitaxial MgO. We observe new low-binding energy states with small spreads in their surface parallel momenta as a result of MgO/Ag(001) interface formation. Under 4.66 eV laser excitation, the quantum efficiency of MgO/Ag(001) is a factor of 7 greater than that of clean Ag(001), revealing the utility of such heterojunctions as advanced photocathodes.
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Affiliation(s)
- Timothy C Droubay
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Scott A Chambers
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Alan G Joly
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Wayne P Hess
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Karoly Németh
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA and Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616, USA
| | - Katherine C Harkay
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Linda Spentzouris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA and Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616, USA
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