Calculation of the excitation cross sections for the 1 Sigma u+ and C 1 Pi u+ states in e-H2 scattering at 60 eV.

Abstract

Integral cross sections have been calculated for the dipole-allowed transitions from X $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ to the $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ and the C $^{1}\mathrm{\ensuremath{\Pi}}_{\mathrm{u}}^{+}$ states in electron--hydrogen-molecule scattering at 60 eV. Experimental data and a universal function [A. Z. Msezane and I. A. Sakmar, Phys. Rev. A 49, 2405 (1994)], which can extrapolate the generalized oscillator strength through the nonphysical region to ${\mathit{K}}^{2}$ (momentum transfer squared) =0, have been used in the calculation. A better agreement between theoretical results and experimental data has been achieved by using the universal function in the range of small scattering angles (\ensuremath{\theta}10\ifmmode^\circ\else\textdegree\fi{}). The results show that the extrapolation used by experimentalists underestimated the differential cross sections (DCS's) at small scattering angles. Our calculation suggests that the universal function can be used to extrapolate the DCS for the electron-molecule scattering down to 0\ifmmode^\circ\else\textdegree\fi{} at high energy.