Linearized secondary-electron cascades from the surface of metals. III. Line-shape synthesis

Linearization of the secondary-electron cascade from the surface of a metal is used to obtain a two-parameter fit ($A$,$m$) to the background of a spectral line: $j_c\mathrm{}\left(E\right)=\frac{A}{E^m}$, where $j_c\mathrm{}\left(E\right)\mathrm{}$ is the energy-dependent ($E$) cascade current $j_c$. This function, evaluated above a spectral line threshold ($E\ge E_T$), is extended by analytic continuation into the region of the spectral line ($E\le E_T$) and subtracted as an approximation to the background. The resulting line then is narrowed by deconvolution of an instrument-specimen response function to remove inelastic-scattering effects that accompany elastic emission at energies characteristic of the spectral feature. An integral correction is described that can be used to extend further the effective correction. Application of these procedures in line-shape synthesis are demonstrated with secondary-electron spectra from a Cu(100) "clean" surface for two types of problems: (i) high-resolution spectroscopy with a goal of obtaining, for example, final-state effects in Auger electron lines, and (ii) low-resolution spectroscopy with a goal of obtaining a reasonable measure of the elastic constituents of emission which could serve, for example, as a basis for quantitative surface analysis. The high-resolution spectra for Auger electron emission accompanying the decay of core holes in $L_2$ and $L_3$ levels of Cu are compared with photoelectron-spectroscopy results reported in the literature. The corresponding spectra for $M_1$, $M_2$, and $M_3$ core holes are compared with other electron-excited Auger spectra reported in the literature.