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W.S.M. Werner:
"Obtaining quantitative information on surface excitations from reflection electron energy loss spectra (REELS)";
Surface and Interface Analysis, 35 (2003), 347 - 353.

A new analysis of reflection electron energy-loss spectroscopy (REELS) spectra is presented. Assuming
inelastic scattering in the bulk to be quantitatively understood, this method provides the distribution of
energy losses in a single surface excitation in absolute units without the use of any fitting parameters.
For this purpose, REELS spectra are decomposed into contributions corresponding to surface and volume
excitations in two steps: first the contribution ofmultiple volume excitations is eliminated from the spectra
and subsequently the distribution of energy losses in a single surface scattering event is retrieved. This
decomposition is possible if surface and bulk excitations are uncorrelated, a condition that is fulfilled for
medium-energy electrons because the thickness of the surface scattering layer is small compared with the
electron elastic mean free path. The developed method is successfully applied to REELS spectra of several
materials. The resulting distributions of energy losses in an individual surface excitation are in good
agreement with theory. In particular, the so-called begrenzungs effect, i.e. the reduction of the intensity of
bulk losses due to coupling with surface excitations near the boundary of a solid-state plasma, becomes
clearly observable in this way. Copyright . 2003 John Wiley & Sons, Ltd.
KEYWORDS: reflection electron energy-loss spectroscopy (REELS); electron scattering; elastic; inelastic; surface excitation

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