Abstract. The total cross section, , for electron capture by Na⁺ ions from oriented coherent elliptic states (CES) of Li with principal quantum number n = 25 was studied experimentally for impact perpendicular to the minor axis of the elliptic orbit. The remaining geometrical parameters of the CES, which are the eccentricity, e , and the angle, , between the major axis and the beam direction, were varied in the course of the experiments, as was the reduced impact velocity v _r = nv , where v is the projectile velocity in atomic units. Several representative cuts were chosen within the parameter space (v _r ,e , ) = (0.74-2.09, 0-1, 0-2 ). The velocity range includes the region of matching velocities (v _r 1) where for given geometrical parameters attains its maximum value and the high-velocity region where is a strongly decreasing function of v _r . The cross section depends sensitively on each geometrical parameter, and the dependences change dramatically as v _r is varied. The spatial distribution of the CES apparently governs in some region of parameter space (v _r ,e , ) and in another the momentum distribution prevails.

Print publication: Issue 5 (14 March 2000)
Received 6 December 1999