Inelastic Interactions of Low-Energy Electrons with Organic Solids: Simple Formulae for Mean Free Paths and Stopping Powers

A theoretical description of the inelastic interactions of low-energy electrons (E¿10 keV) with solid organic insulators is presented. The response of the valence electrons to energy and momentum transfers is inferred from a model for the energy-loss function with parameters fixed by optical data. With this model energy-loss function, inverse mean free path and stopping power due to interactions with the valence electrons are calculated for several organic solids. Contributions to the inverse mean free path and stopping power due to K-shell ionization in carbon, nitrogen, and oxygen are obtained from theoretical atomic generalized oscillator strengths. Simple, analytical formulae are deduced which allow predictions of mean free paths and stopping powers for electrons in the energy range 100 eV¿E¿10 keV to be made for a large group of organic solids.