Electron Scattering by Thin Foils for Energies Below 10 kev

The transmission (${\eta }_T$) of electrons through thin films of C, ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$, Al, Ni, Ag, and Au, together with their distribution in angle and energy, were measured in a spherical retarding-potential analyzer. The distributions were characterized by average and most probable scattering angle, average and most probable fractional energy loss, etc. The dependence of these variables on initial energy ($E_p$), film thickness, and material was investigated. For sufficient film thickness, the transmitted energies, the scattering angles and ${\eta }_T$ can be represented as universal functions of the reduced energy, $\frac{E_p}{E_c}$, where $E_c$ is the critical $E_p$ for the onset of transmission. Direct relations exist between ${\eta }_T$, scattering angles, and energy losses for the complete range of scattering from small-angle scattering to total diffusion. The dependence of ${\eta }_T$ and average fractional energy loss on $Z$ is consistent with published results on backscattering coefficient and energy loss for thick layers. An estimate of the mean free path for inelastic collisions proves to be in good agreement with the predictions of the Bohr-Bethe theory. Range-energy relations are almost independent of $Z$ when the range is measured in mass per unit area.