Dependence of electron loss cross section on the alignment and orientation of elliptic Rydberg states

Ionization and capture of an electron from elliptic H(n = 4) states in collisions with protons have been studied by means of close-coupling calculations for relative velocities in the range of 1.0 to 3.0. Within this velocity range we show that ionization and capture cross sections behave oppositely to each other as either the eccentricity, e, or the orientation angle, phi, between the beam and the classical plane of the elliptic orbital is varied. Thus the total electron loss is shown to depend only weakly on e and phi. Also the dependence of the electron loss cross section on the alignment angle, gamma, between the major axis of the elliptic state and the beam axis is studied. The theoretical calculations for the dependence of the relative capture cross sections on e and phi are shown to be in good agreement with experimental observations for Na+ + Li(n = 25) collisions at the same relative collision velocities. We suggest that the gamma dependence of the capture cross section as well as the dependence of the ionization process on e, phi and gamma should be measured.