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Title: Absorption spectroscopy with sub-angstrom beams. ELS in STEM

Abstract

Electron-energy loss spectroscopy (EELS) performed using a modern transmission scanning electron microscope (STEM) now offers sub-nanometre spatial resolution and an energy resolution down to 200 meV or less, in favourable cases. The absorption spectra, which probe empty states, cover the soft x-ray region and may be obtained under conditions of well-defined momentum transfer (angle-resolved), providing a double projection onto crystallographic site and symmetry within the density of states. By combining the very high brightness of field-emission electron sources (brighter than a synchrotron) with the high cross-section of electron scattering, together with parallel detection (not possible with scanning x-ray absorption spectroscopy), a form of spectroscopy ideally suited to the study of nanostructures, interfacial states and defects in materials is obtained with uniquely high spatial resolution. We review the basic theory, the relationship of EELS to optical properties and the dielectric response function, the removal of multiple scattering artefacts and channelling effects. We also consider applications in the light of recent developments in aberration corrector and electron monochromator design. Furthermore, examples are cited of inner-shell spectra obtained from individual atoms within thin crystals, of the detection of interfacial electronic states in semiconductors, of inner-shell near edge structure mapped with sub-nanometre spatial resolutionmore » in glasses and of spectra obtained from individual carbon nanotubes, amongst many others.« less

Authors:
 [1]
  1. Arizona State Univ., Tempe, AZ (United States)
Publication Date:
Research Org.:
Arizona State Univ., Tempe, AZ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1158698
Report Number(s):
DOE-ASU-45996
Journal ID: ISSN 0034-4885
DOE Contract Number:
FG03-02ER45996
Resource Type:
Journal Article
Resource Relation:
Journal Name: Reports on Progress in Physics; Journal Volume: 69; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Spence, John C.H. Absorption spectroscopy with sub-angstrom beams. ELS in STEM. United States: N. p., 2006. Web. doi:10.1088/0034-4885/69/3/R04.
Spence, John C.H. Absorption spectroscopy with sub-angstrom beams. ELS in STEM. United States. doi:10.1088/0034-4885/69/3/R04.
Spence, John C.H. Wed . "Absorption spectroscopy with sub-angstrom beams. ELS in STEM". United States. doi:10.1088/0034-4885/69/3/R04.
@article{osti_1158698,
title = {Absorption spectroscopy with sub-angstrom beams. ELS in STEM},
author = {Spence, John C.H.},
abstractNote = {Electron-energy loss spectroscopy (EELS) performed using a modern transmission scanning electron microscope (STEM) now offers sub-nanometre spatial resolution and an energy resolution down to 200 meV or less, in favourable cases. The absorption spectra, which probe empty states, cover the soft x-ray region and may be obtained under conditions of well-defined momentum transfer (angle-resolved), providing a double projection onto crystallographic site and symmetry within the density of states. By combining the very high brightness of field-emission electron sources (brighter than a synchrotron) with the high cross-section of electron scattering, together with parallel detection (not possible with scanning x-ray absorption spectroscopy), a form of spectroscopy ideally suited to the study of nanostructures, interfacial states and defects in materials is obtained with uniquely high spatial resolution. We review the basic theory, the relationship of EELS to optical properties and the dielectric response function, the removal of multiple scattering artefacts and channelling effects. We also consider applications in the light of recent developments in aberration corrector and electron monochromator design. Furthermore, examples are cited of inner-shell spectra obtained from individual atoms within thin crystals, of the detection of interfacial electronic states in semiconductors, of inner-shell near edge structure mapped with sub-nanometre spatial resolution in glasses and of spectra obtained from individual carbon nanotubes, amongst many others.},
doi = {10.1088/0034-4885/69/3/R04},
journal = {Reports on Progress in Physics},
number = 3,
volume = 69,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
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