Electron-impact excitation of then=2level of atomic hydrogen at low incident energies

Abstract
Excitation (n=2 level) of the hydrogen atom by electron impact has been studied by using a Callaway-type variant of the polarized-orbital method. The incident wave contains the effect of exchange polarization. Two sets of differential cross sections at three incident energies near the threshold have been obtained. Our results of model II are in good agreement with measured values. The results of our model I are unsatisfactory at large scattering angles.