Moments of the dipole oscillator strength distribution and mean excitation energies of helium.

Abstract

The S(\ensuremath{\mu}) and L(\ensuremath{\mu}) moments of the dipole oscillator strength distribution and the associated mean excitation energies ${\mathit{I}}_{\mathrm{\ensuremath{\mu}}}$ have been calculated for the helium atom using the polarization-propagator formalism. It is found that, if correlation is included, agreement with experimental and other theoretical values is good. The mean excitation energy for stopping is found to be ${\mathit{I}}_{0}$=42.41 eV.