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Title: Low energy electron diffraction using an electronic delay-line detector

Abstract

A low energy electron diffraction (LEED) instrument incorporating a delay line detector has been constructed to rapidly collect high-quality digital LEED images with low total electron exposures. The system uses a position-sensitive pulse-counting detector with high bias current microchannel plates. This delay-line detector combined with a femtoampere electron gun offers a wide range of flexibility, with electron dosing currents ranging from 0.15 pA to 0.3 fA. Using the highest current setting and collecting 1x10{sup 6} counts per image, individual LEED images can be completed in 4 s with an acquisition rate of 250 kHz and a total electron exposure of 5x10{sup 6} electrons. Under the latter conditions, images can be collected in 20 min with an acquisition rate of 1 kHz with a total electron exposure of 2x10{sup 6} electrons. An angular width of 0.13 deg. at 108 eV is demonstrated, which means that domain sizes as large as 600 A can be resolved, depending on the surface quality of the crystal. The system electronics collect 2048x2048 pixel images with a spatial resolution of about 75 {mu}m. The dynamic range of this system is 32 bits/pixel (limited only by physical memory). The construction of the detector results in a 'plus'-shapedmore » artifact, which requires that, for a given sample orientation, two images be taken at a relative angle of 45 deg. Identical current-voltage curves from an MgO(111)1x1 H terminated sample, taken during several hours of exposure to the low current electron beam, demonstrate minimal electron induced H desorption.« less

Authors:
; ; ; ; ; ;  [1];  [2];  [3]
  1. Laboratory for Surface Studies and Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States)
  2. (Canada)
  3. (Germany)
Publication Date:
OSTI Identifier:
20778736
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 2; Other Information: DOI: 10.1063/1.2170078; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ELECTRIC CONDUCTIVITY; ELECTRON BEAMS; ELECTRON DIFFRACTION; ELECTRON GUNS; ELECTRONS; IMAGES; KHZ RANGE 01-100; MAGNESIUM OXIDES; SPATIAL RESOLUTION

Citation Formats

Human, D., Hu, X.F., Hirschmugl, C.J., Ociepa, J., Hall, G., Jagutzki, O., Ullmann-Pfleger, K., OCI Vacuum Microengineering, London, Ontario N5W 4R3O, and Roentdek GmbH, 65779 Kelkheim. Low energy electron diffraction using an electronic delay-line detector. United States: N. p., 2006. Web. doi:10.1063/1.2170078.
Human, D., Hu, X.F., Hirschmugl, C.J., Ociepa, J., Hall, G., Jagutzki, O., Ullmann-Pfleger, K., OCI Vacuum Microengineering, London, Ontario N5W 4R3O, & Roentdek GmbH, 65779 Kelkheim. Low energy electron diffraction using an electronic delay-line detector. United States. doi:10.1063/1.2170078.
Human, D., Hu, X.F., Hirschmugl, C.J., Ociepa, J., Hall, G., Jagutzki, O., Ullmann-Pfleger, K., OCI Vacuum Microengineering, London, Ontario N5W 4R3O, and Roentdek GmbH, 65779 Kelkheim. Wed . "Low energy electron diffraction using an electronic delay-line detector". United States. doi:10.1063/1.2170078.
@article{osti_20778736,
title = {Low energy electron diffraction using an electronic delay-line detector},
author = {Human, D. and Hu, X.F. and Hirschmugl, C.J. and Ociepa, J. and Hall, G. and Jagutzki, O. and Ullmann-Pfleger, K. and OCI Vacuum Microengineering, London, Ontario N5W 4R3O and Roentdek GmbH, 65779 Kelkheim},
abstractNote = {A low energy electron diffraction (LEED) instrument incorporating a delay line detector has been constructed to rapidly collect high-quality digital LEED images with low total electron exposures. The system uses a position-sensitive pulse-counting detector with high bias current microchannel plates. This delay-line detector combined with a femtoampere electron gun offers a wide range of flexibility, with electron dosing currents ranging from 0.15 pA to 0.3 fA. Using the highest current setting and collecting 1x10{sup 6} counts per image, individual LEED images can be completed in 4 s with an acquisition rate of 250 kHz and a total electron exposure of 5x10{sup 6} electrons. Under the latter conditions, images can be collected in 20 min with an acquisition rate of 1 kHz with a total electron exposure of 2x10{sup 6} electrons. An angular width of 0.13 deg. at 108 eV is demonstrated, which means that domain sizes as large as 600 A can be resolved, depending on the surface quality of the crystal. The system electronics collect 2048x2048 pixel images with a spatial resolution of about 75 {mu}m. The dynamic range of this system is 32 bits/pixel (limited only by physical memory). The construction of the detector results in a 'plus'-shaped artifact, which requires that, for a given sample orientation, two images be taken at a relative angle of 45 deg. Identical current-voltage curves from an MgO(111)1x1 H terminated sample, taken during several hours of exposure to the low current electron beam, demonstrate minimal electron induced H desorption.},
doi = {10.1063/1.2170078},
journal = {Review of Scientific Instruments},
number = 2,
volume = 77,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}