Elastic electron reflection for determination of the inelastic mean free path of medium energy electrons in 24 elemental solids for energies between 50 and 3400 eV

Abstract

Abstract Elastic electron backscattering coefficients have been measured for 24 elemental solids (Ag, Al, Au, Be, Bi, C, Co, Cu, Fe, Ge, Mg, Mn, Mo, Ni, Ta, Te, Ti, Pb, Pd, Pt, Si, V, W and Zn) for energies between 50 and 3400 eV. Values for the electron inelastic mean free path (IMFP) were derived from the experimental intensities on the basis of a simple physical model that accounts for bulk elastic and inelastic scattering only. The internal consistency of the data set and the evaluation procedure is satisfactory for energies >150 eV. For energies ≥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 the linear response theory [Surf. Interface Anal. 21 (1994) 165]. We also compare the parameters β (being related to the total dipole matrix elements for inelastic scattering) and γ (determining the details of the energy dependence of the IMFP) that appear in the Bethe equation with corresponding results based on optical data. Both parameters were found to agree well with the earlier analysis by Tanuma et al. [Surf. Interface Anal. 21 (1994) 165] within the statistical accuracy of the present analysis. Experimental data on the recoil energy in elastic scattering were also analyzed and compared with detailed results of Monte Carlo simulations of this phenomenon. The recoil energies are correctly predicted to within 10% by the single deflection model based on the Rutherford cross section.