The photoionization of the hydrogen molecule from the ground electronic and vibrational state

Abstract

The photoionization cross section of the hydrogen molecule is calculated for wavelengths between the threshold (804 Å if the initial state is rotationless) and 430 Å. The Weinbaum approximation is used for the initial electronic state, and in the final state the system is taken to consist of an H2+ ion in the 1sσg ground electronic state and a free electron moving in a field which includes the contribution from the quadrupole moment of the ion. Simplifying approximations are made in the treatment of the rotational and, in some of the calculations, also of the vibrational states. It is believed, however, that the most important source of error is the uncertainty in the phase shift of the continuum pσ orbitals, and because of this the cross sections may be in error by up to 12%. The results agree fairly well with the experimental results by Wainfan, Walker and Weissler, and by Cook and Metzger.