XE-L AND M X-RAY-EMISSION FOLLOWING XE-44-48+ ION IMPACT ON CU SURFACES

The x-ray emission following the impact of highly charged Xe(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 21 -nl', 31 -nl', and 41 -nl' (n less-than-or-equal-to 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 (k(i)) for the states Q = 1s1k2s2k2p3k3s4k3p5k3d6k4s7k4p8k4d9k4f10k5s11k5p12k. 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.