STATE-SELECTIVE RYDBERG CHARGE-TRANSFER AND IONIZATION IN LOW-ENERGY ION-ATOM COLLISIONS

The Classical Trajectory Monte Carlo (CTMC) simulation method with a c ore modified interaction potential has been used to study the single c harge transfer in Na+ and Ar+ ions colliding with a variety of state s elected Na Rydberg atom targets (n=24, 28, 33, 40 and l=2) in the redu ced velocity region v=0.2-2.0. The experimentally observed structures in the total capture cross section versus reduced velocity curves are reproduced by CTMC method. The distribution of final capture state has got two peaks viz. first one at n(f) = n(i) and the second one at a h igher n(f) depending on the initial angular momentum in the velocity r egime 0.4-0.6. These structures have been explained in terms of quasim olecular-ion formation and a classical model proposed by Roy et al. (B .N. Roy, D.N. Tripathi, D.K. Rai, Phys. Rev. A 5 (1972) 1252). The CTM C ionization cross section results are benchmarked with the recent exp erimental measurement of Makarov et al. (O.P. Makarov, D.M. Homan, O.P . Sorokina, K.B. MacAdam, in: F. Aumayr, G. Betz, H.P. Winter (Eds.), Proceedings of the 20th International Conference on the Physics of Ele ctronics and Atomic Collisions, Vienna, 1997, p. FR052) for Na+-Na(24d ). (C) 1998 Elsevier Science B.V. All rights reserved.