Excitation of positive ions by heavy particles.

Abstract

The Coulomb-Born approximation has been used to study the excitation of positive ions by heavy-particle impact. Slater-type wave functions are used for the ionic target states. This choice enables us to calculate the excitation rate coefficients between arbitrary initial and final states. We calculate the differential and total cross sections and alignment parameters for excitation of ${\mathrm{He}}^{+}$ ions from the ground state to the 2p state by proton impact. The alignment parameters for the projectile velocity range considered here are found to be positive in contrast to negative values of the corresponding parameters for electron-impact excitation of the same target states.