Velocity dependence of total charge transfer from state-selected Na Rydberg targets

Relative measurements of total charge transfer in Na + +Na(n i l) collisions at 30 to 2000 eV for selected s and d Rydberg states, n i =22-41, are reported. The cross sections fall off with increasing reduced velocity (v=v ion /v e ) more gradually than H + +H(1s) capture below v=1. The mean functional dependence agrees with classical trajectory Monte Carlo (CTMC) calculations, but previously unreported bumps occur at reduced velocities near 0.5 and 0.8. The validity of high-n CTMC calculations for low reduced velocity is discussed.