Glauber cross sections for excitation of the2P1state of helium by electron impact

Abstract

Recently developed analytic methods, which reduce the Glauber amplitude for charged-particle-neutral-atom collisions to a one-dimensional integral representation involving modified Lommel functions, are used to evaluate the cross sections for the direct excitation of the $2^{1}P$ state of helium by electron impact with incident energies from 55.5 to 900 eV. The theoretical results for the differential and total excitation cross sections are in good agreement with the experimental data. In particular, the Glauber theory predicts a peak value for the total excitation cross sections around 80 eV which is consistent with the existing experimental findings, whereas other theoretical models give monotonically increasing values with decreasing energy below 100 eV.