The energy dependence of a diffusion model of an electron probe into solid targets

The penetration and energy loss characteristics of an electron probe with energies 1 and 10 3 keV in solid targets are analysed by using the potential function of the power and exponential forms of the potential function with a screened atomic radius for scatterings. Then, the diffusion effect due to multiple collisions is combined with the energy retardation in accordance with a modified Thomson-Whiddington law, with the scattering cross-section in the Lenard absorption law, to give consistent expressions for the variation of the transmission fraction eta T and back-scattering fraction eta B with depth y=x/R together with the diffusion depth y D and the maximum energy loss depth y E normalised by the penetration range R as a function of the parameter gamma (which is a function of the incident energy and the atomic number). Diffusion is considered to take place through a hemisphere with a centre located at the most probable energy dissipation depth y C , related to the diffusion depth Y D .