The alignment and orientation effects for charge exchange in 1-1.5 keV collisions are studied by semiclassical close-coupling calculations employing adiabatic molecular data and a common electron translation factor. The differential cross sections from Na(3s) to Li(2s) and Li(2p) are compared to experiment, a large orientation eRect is predicted for charge exchange to Li(Zp,,). From Na(3p) the charge exchange is important only to the Li(Zp) channel, the corresponding alignment and orientation effects are calculated. The orientation effect follows the propensity rules. The formulae for total and differential cross sections for a transition from aligned p to p state or from odented p to p state are derived. Two differential total cross sections for oriented prl to pi, states can be defined, the same for aligned pi45" to p*45" states. The important role of the translation factor is discussed and a four state model is able to describe charge exchange from Na(3p) to Li(2p) at large impact parameters,

Classical trajectory Monte Carlo calculations have been performed for collisions of protons with oriented Na*(3p) atoms. The collision energy range is 1 to 3 keV amu-1. The authors tested the effect of the initial polarization of the Na atom on the charge exchange process. The charge exchange probability shows considerable enhancement for impact parameters larger than 12 au if the electronic angular momenta of the electron and of the incident ion (with respect to the Na nucleus) are in the same direction.

The elecmn capture process from Na*(3pil) atoms by a proton has been sludied both classically and semiclassicaUy in the energy range from 1 to IO keV. In the classical model.we have developed a -body classical trajectory Monte Carlo ( m c ) method with both aCoulomb potential and a model potential for the e--Nat interaction. In the semiclassical model, an adiabatic molecular basis including an elecvon translation factor is employed to describe the elecmnic wavehclion. When the e--Na+ interaction is described by a model potena. at large impact parameter the m c probabilities are in good ag?xement with the semiclassical molecular probabilities at low energies and with the semiclassical atomic probabilities at higher energies.

In the energy range of a few keV the orientation and alignment in electron capture by proton impact from polarized Na*(3p) atoms is studied in a semiclassical molecular model. The adiabatic basis functions, obtained using a model potential method, are modified by a common electron translation factor. The orientation effect is interpreted in terms of a three-state molecular model at large impact parameters 10 au(b(20 au even though the detailed study of the total cross sections requires at least 14 states of positive symmetry.

Abstract. The semi-classical molecular model is applied to study the charge exchange processes in the H +-Na 3 p and Li+-Na 3p systems in the keV energy range. The dependence of the charge exchange on the orientation and the alignment of the initial or final state is obtained for the transition probabilities and for the differential cross sections. The 14 state present model for the H+-Na system is in good agreement with the experimental differential cross sections. The alignment is explained by orientation occurring in the transfer region. The cross sections predicted with a 28 state model for Li+-Na exhibit similar behaviour as for H+-Na.