STABILIZED DOUBLE-ELECTRON CAPTURE IN NE10+-HE COLLISIONS - VELOCITY DEPENDENCE OF RYDBERG-ELECTRON N,L-DISTRIBUTIONS

The distribution over the n states populated by double-electron capture in Ne10+-He collisions has been determined in the energy range of 0.9-9 keV/u by analyzing the radiative decays of projectile Rydberg transitions. It has been found to be in fair agreement with predictions of the autotransfer-to-Rydberg-states model of Roncin et al. [J. Phys. B 26, 4181 (1993)]. Double-capture stabilization ratio R(S), defined as the ratio of true double capture sigma(TDC) to the sum of sigma(TDC) and autoionizing double capture sigma(ADC), has been studied at various energies. A slight enhancement of R(S) (35-50 %) and an increase by a factor of 5 of the cross sections for emission of optical transitions from (3,n) Rydberg states have been found as the projectile velocity decreases from 0.6 to 0.19 a.u. We propose a tentative explanation following a model of postcollisional satellization of Rydberg electrons.