Inelastic Atomic Scattering of 0.1-, 0.2-, 0.4-, and 3.0-MeV Electrons

Spectral data obtained with a magnetic spectrometer are presented for inelastic electron scattering from thin targets of carbon, copper, and gold at incident electron energies of 0.1, 0.2, 0.4, and 3.0 MeV, for scattering angles between 20° and 120°. For angles less than 90°, each spectrum consists of (a) a Møller line which has a half-width that increases with atomic number and which yields an experimental cross section that agrees within experimental error with the theoretical Møller cross section, and (b) a low-energy continuum which rises steeply at energies less than 40 keV. For angles greater than 90°, the Møller line which is kinematically forbidden vanishes, but the steeply rising continuum remains. This continuum may arise from single electron-atom scattering and from multiple scattering in the target. The latter process depends on target thickness. The experimental results for this low-energy continuum tend to confirm that the multiple-scattering effects as calculated by Ford and Mullin dominate the single-scattering process as calculated by Weber, Deck, and Mullin, and by Kolbenstvedt and Cooper even for an 11-μg/${\mathrm{cm}}^2$ carbon target which was the most favorable case for studying the single-scattering process. Because of multiple scattering, accurate experimental data for the low-energy continuum produced by single electron-atom inelastic scattering can best be obtained with gas targets.