Energy Deposition of keV Electrons in Light Elements

The Monte Carlo simulation method has been used to investigate the spatial distribution of deposited energy for 1–10 keV electrons incident on solid hydrogen, nitrogen, neon, silicon, aluminum, and argon. In the simulation, elastic scattering cross sections are calculated exactly using the single‐atom crystalline potentials.

Inelastic energy loss processes for hydrogen are based on the ionization cross section from Green and Sawada [J. Atmos. Terr. Phys. 34, 1719 (1972)] and the gas‐phase stopping power from Parks et al. [Nucl. Fus. 17, 539 (1977)]. For the heavier materials a modification of Gryziński’s [Phys. Rev. A 138, 305 (1965); 138, 322 (1965); 138, 336 (1965)] semiempirical expression for each core and valence electron excitation is used.

The energy‐deposition distribution of keV electrons and the ionization distribution of weakly bound electrons are practically equal, whereas the penetration depth distribution extends deeper into the material than the energy‐deposition distribution. The energy‐deposition distributions of keV electrons for light materials, except for hydrogen, can be represented quite well by a universal distribution.

In addition, accurate Gaussian approximations for the different materials in the entire energy region from 1 to 10 keV have been evaluated. Parameters such as the mean penetration depth and the mean energy‐deposition depth are included as well.