Electronic excitation of the a3 ∑ g+ and c3Πu states of H 2 by electron impact using the method of continued fractions

Abstract

In the present work we use a multichannel extension of the method of continued fractions (MCF) to study the low-energy electron-impact excitation in linear molecules at the two-state close-coupling level. In particular we have calculated the excitation cross sections for the X 1 ∑ g + → a 3 ∑ g + and X 1 ∑ g + → c 3 Π u transitions in H 2 for incident energies from near threshold to 30 eV. In our work, in contrast with the early two-state studies of Chung and Lin, no orthogonality constraint between the bound and continuum orbitals is imposed and the one-electron exchange terms are explicitly considered. In general our calculated cross sections are in good agreement with the results of the two-state Schwinger multichannel method. Our results for the a 3 ∑ g + are also in quite good agreement with the available experimental data. However, the cross sections for excitation of the c 3 Π u state differ significantly from the measured values at 20 and 30 eV, where they are available. The disagreement is attributed to the multichannel effects, not accounted for in this study.