The excitation of the 2 3 P state of helium by electron impact

Abstract

Cross-sections for excitation of the 2 3 P state of helium from the ground state have been calculated by the distorted-wave method. The polarization of radiation emitted as a result of the excitation is also calculated. Comparison is made with the corresponding results given by the Born—Oppenheimer approximation. Although there are considerable differences at electron energies below 100 eV these are much less marked than for the excitation of the 2 3 S state. The distorted wave method gives cross-sections in closer agreement with observation but substantial discrepancies still remain. It is difficult, however, to estimate their magnitude with any certainty because there are inconsistencies in the observed data.