The 1¹S to 2¹S and 1¹S to 2¹P excitation of helium by electron impact

Abstract

The R-matrix method calculations of Berrington et al. (1975) and Fon et al. (1979) are extended to the energy ranges 21.4<E<30 eV and 80<E<or=200 eV for the electron impact excitation of 21S and 21P state of helium. Differential and integrated cross sections for these transitions and the ( lambda , chi ) parameters for the 21P excitation are calculated and compared with the recent theoretical calculations and experimental measurements.