Application of the Schwinger Principle to Direct Excitation of Atoms or Ions by Impact of Bare Nuclei at Intermediate Velocities

Abstract

A variational scattering amplitude derived in the impact-parameter formalism is used to investigate the electronic excitation of highly charged ions by ion impact at intermediate velocities. This treatment predicts that the cross sections tend to finite limits when the charge of the projectile increases. This feature is illustrated by the good agreement between our theoretical and experimental results for the excitation of ${\mathrm{Fe}}^{24+}$ by He, N, and Ar. The excitation of H by ${\mathrm{H}}^{+}$ is studied as a check of our theory.