Linearized secondary-electron cascades from the surfaces of metals. II. Surface and subsurface sources

Segmentation of the linearized cascade from a metallic surface was shown in Paper I to be initiated by internal sources. Here the nature of the line shape accompanying the segmentation is related to a distinction between internal sources according to surface and subsurface distributions of their constituents. These sources are assumed to be activated during the decay processes that accompany excitation of bound electrons by passing primary electrons and derive from atomic constituents having distinguishable spatial distributions. The distributions correspond to a surface source if they exist within an inelastic mean free path $l_i\mathrm{}\left(E\right)\mathrm{}$ of the vacuum-solid interface, and are subsurface sources if they exist below this level in the solid. Composite distributions are considered also. Characteristic spectra in the $\frac{logj\left(E\right)\mathrm{}}{log\mathrm{}\left(E\right)\mathrm{}}$ display mode are shown for nitrogen, oxygen, carbon, and sulfur serving as internal sources in nickel and aluminum.