Electron impact excitation of hydrogenic ions

Abstract

Calculations on electron impact excitation of the n=1 and n=2 states of hydrogenic ions have been made for atomic numbers Z ranging from 2 to 100 in a Coulomb-Born approximation in which Dirac wavefunctions are used instead of the more usual Schrodinger ones. All one-body relativistic effects are included, and of the two-body effects, mutual spin-orbit coupling but not magnetic or retardation effects. Relativistic effects are found to contribute 10% to the cross sections for most transitions at Z=25 and up to a factor of 6 at Z=100. The conservation of total spin is investigated and the spin-orbit interaction due to the nuclear potential found to be the most significant cause of changes in total spin except at very high incident electron energies.