Experimental measurements of the surface excitation parameters of Cu, Au, Ni, Ag, Ge and Pd based on Si and other reference standard materials

Surface excitation in electron spectroscopy is characterized by the surface excitation parameter P-se. In electron spectroscopy, the total surface excitation is observed for electrons impinging and reflected elastically (elastic peak electron spectroscopy, EPES) or for backscattered (REELS) electrons. Surface excitation reduces the intensity of the elastic peak and affects the REELS spectra. Experimental determination of the total P-se from EPES spectra is made by measuring the ratio of integrated elastic peak intensities for the sample I-ese and reference material I-ese. This paper presents further development of Tanuma's work for this ratio. P-ser of the reference was calculated with the formula and material parameters of Chen. Monte Carlo simulations were based on the NIST elastic scattering and Tanuma's IMFPs database for the reference samples. This work deals with Cu, Au, Ag, Ni and Pd metals and Ge, used also as standards for electron spectroscopy. Experiments were made with a high-energy resolution spectrometer (HSA), and with a DESA 100 spectrometer (Staib Ltd) with large solid angle for E = 0.2-2 keV. Surface excitation correction factors have been developed for the above metals and Ge, used for reference samples. Their application reduced the differences in IMFPs from Tanuma's values for the uncorrected rms errors Deltalambda(u) (% values) to Deltalambda(c) (corrected) data for Si/Ag (from 21.2 to 6.7%), for Si/Ni (11.4 to 9.8%), and for Si/Cu (13.5 to 5%). A similar improvement was found for Si/Au, Ag/Ni, Ag/Cu and Ag/Au experimental results, using surface excitation correction. Copyright (C) 2004 John Wiley Sons, Ltd.