Electron spectroscopy of Li+-Ne collisions: velocity dependence of Ne 2s and 2p vacancy production

Energy spectra of 15-35 eV electrons ejected from 15-70 keV Li+-Ne collisions have been measured. The lines are assigned to neon configurations of the type K 2s22p4nln'l', K 2s2p5nln'l', K2s2p6nl and K 2s2p5nl. Several lines have not been observed or identified before, and their classification is suggested. The spectral pattern changes drastically with increasing energy. At low energies lines from levels with two 2p vacancies dominate. At high energies only lines with a 2s vacancy are observed. Analysis of this strong velocity dependence of the n = 2 neon subshell correlation shows that the correlation at the 2σ-3σ pseudocrossing obeys the Barat-Lichten rule at low velocity and confirms the prescription of Eichler et al (Phys. Rev.; A14: 707 (1976)) at high velocity. A corresponding critical velocity of upsilonsub(c) is approximately equal to 0.3-0.4 au is derived. (author)