Ag, Ge and Sn reference samples for elastic peak electron spectroscopy (EPES), used for experimental determination of the inelastic mean free path and the surface excitation parameter

Reference samples are needed for experimental determination of the inelastic mean free path (IMFP) of electrons by elastic peak electron spectroscopy (EPES). High‐quality (microcrystalline mirror) Ni reference samples were used for IMFP measurements. For surface excitation parameter experiments, new types of reference samples are needed. They should exhibit pronounced surface‐loss spectra, such as amorphous Ge (aGe), Sn and Ag. A new procedure is presented for their preparation. Microcrystalline Ag and Sn reference samples were deposited on highly polished (by Buehler alumina alpha micropolish 1C) brass (60% Cu, 40% Zn) substrates. Electrolytic deposition was used for Ag and for Sn and resulted in excellent surface quality. The average surface roughness r av was checked by scanning tunnelling microscopy or atomic force microscopy before and after Ar + ion bombardment cleaning. Typical r av values were 4–6 nm for Ag, 3–4 nm for Sn and 2–4 nm for brass substrate. The aGe sample was deposited by magnetron sputtering or by evaporation in a high vacuum on an Si substrate. Its r av was 4–5 nm. The samples were studied by EPES/reflection electron energy‐loss spectroscopy, covering the 0.2–5 keV energy range, with the ESA 31 HSA electron spectrometer. The IMFP of Sn was determined by EPES. The surface excitation parameters for the Si, Ge and Sn samples were determined from their inelastic scattering cross‐section spectra. For Ag the surface excitation parameter was estimated by using the above reference samples. Copyright © 2002 John Wiley & Sons, Ltd.