State-resolved Photodissociation and Radiative Association Data for the Molecular Hydrogen Ion

Abstract

We present state-resolved (electronic, vibrational, and rotational) cross sections and rate coefficients for the photodissociation (PD) of H 2 + and radiative association (RA) of H-H + . We developed a fully quantum mechanical approach within the nonrelativistic Born-Oppenheimer approximation to describe H 2 + and calculate the data for transitions between the ground electronic state 1ss g and the 2ps u , 2pp u , 3ps u , 3pp u , 4ps u , 4fs u , 4fp u , and 4pp u electronic states (i.e., up to H 2 + n = 4). Tables of the dipole-matrix elements and energies needed to calculate stateresolved cross sections and rate coefficients will be made publicly available. These data could be important in astrophysical models when dealing with photon wavelengths (or radiation temperature distributions that are weighted toward such wavelengths) around 100 nm. For example, at these wavelengths and a material temperature of 8400 K, the LTE-averaged PD cross section via the (second electronically excited) 2pp u state is over three times larger than the PD cross section via the (first electronically excited) 2ps u state.