A Predictive Formula for the Electron Stopping Power
Aleksander Jablonski, S Tanuma, Cedric J. Powell
We describe the development of a new analytical formula for the electron stopping power (SP) for electron energies between 200 eV and 30 keV. This formula describes the product of the SP and the inelastic mean free path (IMFP), and is a simple function of atomic number and electron energy. Parameters in the expression were obtained from a fit to SPs and IMFPs computed from experimental optical data for a group of 27 elemental solids, and a mean deviation of 10.4 % was found between SPs from optical data and from the new formula. This mean deviation was less than that found in similar comparisons with SPs from empirical modifications of the Bethe SP equation by Joy and Luo and by Fernandez-Varea et al. We show illustrative comparisons of SPs calculated from optical data, measured SPs, and SPs from the three predictive SP expressions for C, Si, Cu, Pd, and Pt. The three expressions have been generalized to compounds, and we show similar comparisons for indium antimonide and guanine. The new SP expression is believed to be suitable for Monte Carlo simulations with the continuous slowing-down approximation.