Microsc. Microanal. Microstruct. 2, 301-314 (1991)
DOI: 10.1051/mmm:0199100202-3030100

Optimum experimental conditions for quantitative surface microanalysis by reflection electron energy-loss spectroscopy

Zhong Lin Wang^{1, 2} et James Bentley<sup>1

1</sup>  Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6376, U.S.A.
²  Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2200, U.S.A.

Abstract
Experimental conditions for obtaining high quality core-shell ionization edges in reflection electron energy-loss spectroscopy (REELS) are investigated. Under the (600) specular- "mirror" reflection conditions and using the relative ionization cross-section measured from a MgO thin foil in the transmission geometry for collection semi-angle β = 1.2mrad, the chemical composition of MgO (100) surfaces is determined to be NO/NMg = 1.5 ± 0.15. This value is not significantly affected by varying the resonance diffraction conditions near the [001] zone axis, under which the spectra were acquired. An incorrect apparent composition will result if channeling effects along the [011] zone axis are not considered properly. Surface microanalysis is limited by the accuracy of the core-shell effective ionization cross-section (EICS), which depends not only on the property of a single atom but also on the dynamical elastic and inelastic scattering and channeling processes of electrons. An experimental method is outlined by which to measure the relative EICS from a thin foil specimen in the transmission case under the equivalent resonance conditions as in reflection geometry.

PACS
6835D - Composition, segregation; defects and impurities.
6837L - Transmission electron microscopy (TEM) (including STEM, HRTEM, etc.).
0781 - Electron and ion spectrometers.

Key words
Reflection electron microscopy -- EEL spectroscopy -- Core level -- Magnesium oxide -- Surface analysis -- Microanalysis -- Cross sections -- Chemical composition -- Crystal faces -- Ionization edge -- MgO(100)


© EDP Sciences 1991