Alignment and orientation for charge exchange in Li⁺-Na(3s, 3p) collisions: I. Differential and total cross sections

Abstract

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,

Orientation and alignment in charge exchange processes involving sodium atoms studied by semi-classical molecular theory

“…It can be predicted if the electronic angular momentum is conserved or not conserved in the charge exchange process. This effect can be studied in the collision plane on the DCS and on the charge exchange probability, also on the total cross sections [16]. We present here the initial and final orientation effects on the probabilities.…”

“…Recently Classical Trajectory Monte-Carlo method has been developed to study the orientation effects for the H +-Na (3 p) collision [ 14,15 ]. We have performed new calculations for the Li +-Na system with a large molecular basis [16] such that we can now compare the two H +-Na and Li +-Na systems.…”

Numerical treatment of inelastic He++Ne collisions at low energy

“…Within reasonable ranges, this was without significant numerical effect.We conclude especially that the WKB approximation, as we use it, is not worse than the full quantum version. The coupled WKB equations show a certain formal similarity to the coupled equations of the CT or the semiclassical impact-parameter method [19]. We wish to emphasize that this does not introduce the shortcomings of these methods into the present procedure.…”

Orbital alignment dependence of electron transfer cross sections

“…Among these we focus on the L i + -N a (3s, 3p) case for which final state analysis offers interesting new possibilities. Pilot studies in this direction [39,40] indicate that this line of approach may be expected to provide answers to questions such as which trends in the alignment and orientation effects are global, and which are system-specific. This alternative system is the topic of a forthcoming paper in this series.…”