Excitation and ionization of H(2s) by proton impact

Abstract

The two-centre atomic orbital close-coupling expansion method is used to study the excitation and ionization processes in collisions of protons with metastable hydrogen H(2s). The excitation cross sections to n=3 and 4 and the averaged dipole moments are compared with the eikonal impulse distorted wave approximation calculations by Rodriguez and Miraglia and the one-centre expansion calculation by Ford et al. General agreement is found at high impact energies, but the difference in dipole moments between the present calculation and the EIA calculation at low energies is very large. We also examine the propensity rule for the magnetic substate distributions in the excitation cross sections in the 'natural' frame of reference.