L-SHELL RESONANT TRANSFER AND EXCITATION IN NIOBIUM IONS

We have calculated L-shell cross sections for the process of resonant transfer excitation followed by x-ray stabilization (RTEX) in collisions of Nbq+ ions (q=28 32) with H2. The LMn plateau cross section is nearly constant [(4.5 5.2)×10-20 cm2] for q=29 32 and is consistent with the results of the recent experiment by Bernstein et al. [Phys. Rev. A 40, 4085 (1989)] for q=31 and 32, but our results for q=28 30 are substantially larger than experiment. For Ne-like niobium (q=31), the inclusion of RTEX contributions from higher transitions (LNn, LOn, etc.) leads to good agreement with the experiment by Bernstein et al. in the high-energy tail. This implies that only a small contribution is possible from the uncorrelated transfer excitation process. © 1990 The American Physical Society.