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Title: The Boersch effect in a picosecond pulsed electron beam emitted from a semiconductor photocathode

Abstract

The space charge effect has been clearly observed in the energy distributions of picosecond pulse beams from a spin-polarized electron microscope, and was found to depend upon the quantity of charge per pulse. The non-linear phenomena associated with this effect have also been replicated in beam simulations that take into account of a three-dimensional space charge. The results show that a charge of 500 aC/pulse provides the highest brightness with a 16-ps pulse duration, a 30-keV beam energy, and an emission spot of 1.8 μm. Furthermore, the degeneracy of the wave packet of the pulsed electron beam has been evaluated to be 1.6 × 10{sup −5} with a charge of 100 aC/pulse, which is higher than that for a continuously emitted electron beam despite the low beam energy of 30 keV. The high degeneracy and high brightness contribute to the realization of high temporal and energy resolutions in low-voltage electron microscopy, which will serve to reduce radiolysis damage and enhance scattering contrast.

Authors:
; ;  [1];  [2]; ; ; ;  [3];  [4];  [5];  [2];  [1]
  1. Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8603 (Japan)
  2. (Japan)
  3. Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)
  4. High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)
  5. Aichi Synchrotron Radiation Center, Seto 489-0965 (Japan)
Publication Date:
OSTI Identifier:
22590582
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 1; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BRIGHTNESS; ELECTRON BEAMS; ELECTRON MICROSCOPES; ELECTRON MICROSCOPY; EMISSION; ENERGY RESOLUTION; ENERGY SPECTRA; KEV RANGE 10-100; NONLINEAR PROBLEMS; PHOTOCATHODES; SCATTERING; SEMICONDUCTOR MATERIALS; SPACE CHARGE; SPIN ORIENTATION; WAVE PACKETS

Citation Formats

Kuwahara, Makoto, E-mail: kuwahara@imass.nagoya-u.ac.jp, Ujihara, Toru, Saitoh, Koh, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Nambo, Yoshito, Aoki, Kota, Sameshima, Kensuke, Asano, Hidefumi, Jin, Xiuguang, Takeda, Yoshikazu, Nagoya Industrial Science Research Institute, Nagoya 460-0008, and Tanaka, Nobuo. The Boersch effect in a picosecond pulsed electron beam emitted from a semiconductor photocathode. United States: N. p., 2016. Web. doi:10.1063/1.4955457.
Kuwahara, Makoto, E-mail: kuwahara@imass.nagoya-u.ac.jp, Ujihara, Toru, Saitoh, Koh, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Nambo, Yoshito, Aoki, Kota, Sameshima, Kensuke, Asano, Hidefumi, Jin, Xiuguang, Takeda, Yoshikazu, Nagoya Industrial Science Research Institute, Nagoya 460-0008, & Tanaka, Nobuo. The Boersch effect in a picosecond pulsed electron beam emitted from a semiconductor photocathode. United States. doi:10.1063/1.4955457.
Kuwahara, Makoto, E-mail: kuwahara@imass.nagoya-u.ac.jp, Ujihara, Toru, Saitoh, Koh, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Nambo, Yoshito, Aoki, Kota, Sameshima, Kensuke, Asano, Hidefumi, Jin, Xiuguang, Takeda, Yoshikazu, Nagoya Industrial Science Research Institute, Nagoya 460-0008, and Tanaka, Nobuo. 2016. "The Boersch effect in a picosecond pulsed electron beam emitted from a semiconductor photocathode". United States. doi:10.1063/1.4955457.
@article{osti_22590582,
title = {The Boersch effect in a picosecond pulsed electron beam emitted from a semiconductor photocathode},
author = {Kuwahara, Makoto, E-mail: kuwahara@imass.nagoya-u.ac.jp and Ujihara, Toru and Saitoh, Koh and Graduate School of Engineering, Nagoya University, Nagoya 464-8603 and Nambo, Yoshito and Aoki, Kota and Sameshima, Kensuke and Asano, Hidefumi and Jin, Xiuguang and Takeda, Yoshikazu and Nagoya Industrial Science Research Institute, Nagoya 460-0008 and Tanaka, Nobuo},
abstractNote = {The space charge effect has been clearly observed in the energy distributions of picosecond pulse beams from a spin-polarized electron microscope, and was found to depend upon the quantity of charge per pulse. The non-linear phenomena associated with this effect have also been replicated in beam simulations that take into account of a three-dimensional space charge. The results show that a charge of 500 aC/pulse provides the highest brightness with a 16-ps pulse duration, a 30-keV beam energy, and an emission spot of 1.8 μm. Furthermore, the degeneracy of the wave packet of the pulsed electron beam has been evaluated to be 1.6 × 10{sup −5} with a charge of 100 aC/pulse, which is higher than that for a continuously emitted electron beam despite the low beam energy of 30 keV. The high degeneracy and high brightness contribute to the realization of high temporal and energy resolutions in low-voltage electron microscopy, which will serve to reduce radiolysis damage and enhance scattering contrast.},
doi = {10.1063/1.4955457},
journal = {Applied Physics Letters},
number = 1,
volume = 109,
place = {United States},
year = 2016,
month = 7
}
  • The brightness and interference fringes of a spin-polarized electron beam extracted from a semiconductor photocathode excited by laser irradiation are directly measured via its use in a transmission electron microscope. The brightness was 3.8 × 10{sup 7 }A cm{sup −2 }sr{sup −1} for a 30-keV beam energy with the polarization of 82%, which corresponds to 3.1 × 10{sup 8 }A cm{sup −2 }sr{sup −1} for a 200-keV beam energy. The resulting electron beam exhibited a long coherence length at the specimen position due to the high parallelism of (1.7 ± 0.3) × 10{sup −5 }rad, which generated interference fringes representative of a first-order correlation using an electron biprism. The beam also had amore » high degeneracy of electron wavepacket of 4 × 10{sup −6}. Due to the high polarization, the high degeneracy and the long coherence length, the spin-polarized electron beam can enhance the antibunching effect.« less
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