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

Open Access
Publisher Website
Google Scholar
Abstract
©1991 EDP Sciences. Article available at: http://mmm.edpsciences.org or http://dx.doi.org/10.1051/mmm:0199100202-3030100DOI: 10.1051/mmm:0199100202-3030100Experimental 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