Electron capture from elliptic Rydberg states

Recent experiments on electron capture from elliptic Rydberg states have shown that the total electron capture cross section depends strongly on the eccentricity, e, of the elliptic state and the orbit direction of the electron. By carrying out close-coupling calculations for protons colliding with elliptic H(n=3,4,5) atoms we show that the dependence of total capture cross section on e varies weakly with the principal quantum number n. We also present the dependence of the total capture cross section as function of the angle, ψ, between the incoming ions and the classical plane of the elliptic orbital. Both the dependence on e and on ψ are shown to be consistent with the criteria of velocity matching for the electron capture process. (Author)