Electron-impact excitation of silver

Abstract

We measure the differential cross sections (DCSs) for the electron-impact excitation of the combined (two fine-structure levels) resonant $4{d}^{10}5p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2,3/2}$ and $4{d}^{9}5{s}^{2}\phantom{\rule{0.16em}{0ex}}^{2}D_{5/2}$ states in silver from the $4{d}^{10}5s\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}$ ground state. A comparison with the predictions of the relativistic distorted-wave (RDW) approximation model is carried out. Relativistic distorted-wave calculations are performed for each level separately and are combined to compare with the measurements. Both the experimental and theoretical results are obtained at incident electron energies ${E}_{0}$ of 10, 20, 40, 60, 80, and 100 eV and scattering angles \ensuremath{\theta} from 10\ifmmode^\circ\else\textdegree\fi{} up to 150\ifmmode^\circ\else\textdegree\fi{} (experiment) and from 0\ifmmode^\circ\else\textdegree\fi{} to 180\ifmmode^\circ\else\textdegree\fi{} (calculations). Absolute values for the experimental DCSs are obtained by normalizing relative DCSs to theoretical RDW results at 40\ifmmode^\circ\else\textdegree\fi{} at all energies except at 10 eV, where we performed the normalization of the relative DCSs at 10\ifmmode^\circ\else\textdegree\fi{} to our previous small-angle experimental DCS values [S. D. To\ifmmode \check{s}\else \v{s}\fi{}i\ifmmode \acute{c}\else \'{c}\fi{} et al., Nucl. Instrum. Methods Phys. Res. Sect. B 279, 53 (2012)]. The integrated cross sections, which include integral ${Q}_{\mathrm{I}}$, momentum transfer ${Q}_{\mathrm{M}}$, and viscosity ${Q}_{\mathrm{V}}$ cross sections, are determined by numerical integration of the absolute DCSs.