Electron capture and excitation in He+–He(1s2s1,3S) collisions

Abstract

State-selective single-electron capture and excitation processes in collisions of He+ ions with metastable He(1s2s1,3S) excited atoms are investigated by using the two-center atomic orbital close-coupling method in the energy range 0.5–100 keV/u. The expansion basis includes all the states with n ≤ 9, lmax = 4 on the projectile and all the states with n ≤ 5, lmax = 4 on the target, when treating the electron capture and vice versa, when treating the ionization. One-electron model potentials for the singlet and triplet series of states have been used that reproduce the exact energies within an accuracy of 1%–2%. Spin-resolved electron capture and excitation cross sections to nl final states with n ≤ 4 are presented. The origin of differences in the magnitude and energy behavior of spin-resolved cross sections is discussed. The reported cross section results should be useful in the studies of properties of various laboratory and astrophysical helium plasmas.