The x-ray emission following the impact of highly charged ${\mathrm{Xe}}^{\mathit{q}+}$ (q=44–48) ions of 7-keV/q energy on a Cu surface has been measured. Theoretically we have derived an analytic formula which allows us to calculate the 2l-nl’, 3l-nl’, and 4l-nl’ (n≤5), L, M, and N x-ray transition energies averaged over spin and angular-momentum quantum numbers (L and S) as a function of the electron occupation numbers (${\mathit{k}}_{\mathit{i}}$) for the states Q=1${\mathit{s}}_1^{\mathit{k}}$2${\mathit{s}}_2^{\mathit{k}}$2${\mathit{p}}_3^{\mathit{k}}$3${\mathit{s}}_4^{\mathit{k}}$3${\mathit{p}}_5^{\mathit{k}}$3${\mathit{d}}_6^{\mathit{k}}$4s ${}_7{}^{\mathit{k}}{}_{}{}^{}\mathit{p}_8^{\mathit{k}}{}_{}{}^{}$4${\mathit{d}}_9^{\mathit{k}}$4${\mathit{f}}_{10}^{\mathit{k}}$5${\mathit{s}}_{11}^{\mathit{k}}$5${\mathit{p}}_{12}^{\mathit{k}}$. In accordance with our theoretical predictions the observed L x-ray structures shift toward higher energies and increase in intensity relative to the M x rays with increasing charge state. We have also observed an increase in high-energy satellite-line intensities with the increasing number of 2p vacancies. In calculating the radiative-transition probabilities we have found that the dominating electric-dipole transitions for L and M x rays are of the kind 2p-3d and 3d-4f, respectively. A comparison between measured peak positions and calculated transition energies reveals that direct feeding by approximately 13 electrons can explain the main features of the observed x-ray emission spectra.

• Received 24 April 1992

DOI:https://doi.org/10.1103/PhysRevA.47.3983