Electron capture from excited alkali atoms by H + at low energies

Abstract

Charge-transfer cross sections from the initially aligned np-state of alkali atoms by protons have been calculated in the 10 eV to 5 keV amu −1 energy region. The semiclassical impact-parameter method is employed wherein a coupled molecular states expansion, augmented by the plane wave electron translation factor, is used to represent the electronic wave functions. The dependence of the cross section for the formation of the first excited ( n = 2 l) states of H, on the orbital geometry and the alignment of the initial state, is discussed. The cross sections are sensitive to the variation of the spatial alignment of the electron charge distribution. The cross section decreases with increasing initial alignment at lower energies, and at higher energies, the situation is reversed. At E = 0.05 keV amu −1, the cross section is isotropically aligned. At this energy, the cross section is the same for both the initial states Σ and Π. The orientation of the excited H(2p) orbital resulting from electron capture is also given.