Electron inelastic mean free path measured by elastic peak electron spectroscopy for 24 solids between 50 and 3400 eV

Elastic electron backscattering coefficients have been measured for 24 elem ental solids (Ag, Al, An, Be, Bi, C, Co, Cu, Fe, Ge, Mg, Mn, Mo, Ni, Ta, Te , Ti, Pb, Pd, Pt, Si, V, W, Zn) for energies between 50 and 3400 eV. Values for the electron inelastic mean free path (IMFP) were derived from the exp erimental intensities on the basis of a simple physical model for elastic b ackscattering that accounts for bulk elastic and inelastic scattering only. For energies greater than or equal to 200 eV the IMFP values were found to be well described by the Bethe equation for inelastic scattering, as found earlier by analysis of optical scattering data with the aid of linear resp onse theory (Surf. Interf. Anal. 21 (1994) 165). The parameters beta and ga mma appearing in the Bethe equation are compared with corresponding results derived from optical data. Both, the parameter beta, that is related to th e total dipole matrix element for inelastic scattering, as well as the para meter gamma, that describes the energy dependence of the IMFP, were found t o coincide with the results based on optical data within the experimental a ccuracy of our analysis. Since the present analysis of electron scattering data is entirely free of linear response theory, the present results may be regarded as an independent test of the previous analysis based on optical scattering data. (C) 2000 Elsevier Science B.V. All rights reserved.