STATE-SELECTIVE CAPTURE IN COLLISIONS BETWEEN IONS AND GROUND-STATE AND EXCITED-STATE ALKALI-METAL ATOMS

Total cross sections for state-selective electron capture in collisions between ions and alkali-metal atoms have been calculated by means of a three-body classical-trajectory Monte Carlo (CTMC) method using model potentials to describe the electronionic-core interactions. Calculations have been performed for Na+-Na(28d) collisions and for N5+ and Ar8+-Cs(6s) collisions. The collision velocity range corresponds to 0.5vp/ve2, where vp is the projectile velocity in the laboratory frame and ve is the initial orbital velocity of the electron bound to the alkali-metal core. In the case of Na++Na(28d) collisions, calculations of the final n,l,m distributions show the importance of the electron-capture cross sections into states with m>1. For the case of multiply charged ionCs(6s) collisions, a predominance of electron capture to nearly circular states (large l values) is predicted for cross sections near the maximum of the n distribution. When the e - Cs+ interaction is described by a realistic model potential, the CTMC calculations are found to be in good agreement with recent measurements of the final n values that are predominantly populated after single-electron capture. © 1990 The American Physical Society.