Inelastic high-energy electron scattering from a hydrogen molecule. I. X–B and X–E transitions

Abstract

Generalized oscillator strengths have been computed for high-energy electron scattering by H 2 • The optically allowed transitions from the electronic ground state (X 'I.+) to the B 'I.+ state and the optically forbidden transitions to the E'I/ state have been considered. Accurate wave functions expanded in explicitly correlated Gaussian functions were used to describe the electronic states of H 2 • The dependencies of the form factors on the molecular orientation, the momentum transfer, and the internuclear separation are discussed. For the X -B transitions the form factors have been integrated over the internuclear separation with accurate vibrational wave functions. A comparison of the obtained values with those computed assuming the Franck-Condon approximation has shown that the latter are not always reliable. In the region of a very small momentum transfer, the present results are found to be very close to the accurate values obtained for optical transition probabilities to the B state with wave functions depending explicitly on odd and even powers of the interelectronic distance.