Rovibrationally-resolved photodissociation of HD

The photodissociation of most molecules is typically obtained through pre-computed,exponentially-attenuated fitted photo rates, whose assumptions are likely to describe fewastronomical environments. Furthermore, calculations of cross sections for the photodissociationof the isotopomer of molecular hydrogen, HD, are currently available only for the J = 0 levels ofthe ground electronic state. Explicit calculations of cross sections from all rovibrational states arenecessary in order to compute HD photo-destruction rates for any environment and radiationfield. To this end, we have directly calculated the partial cross sections for the Lyman andWerner transitions of HD from all 400 rovibrational levels of the ground electronic state into thecontinua of the upper electronic states. This required input of potential curves and dipoletransition moments derived by standard ab initio techniques. The partial cross sections werecalculated for a number of wavelengths ranging from 100 to the dissociation threshold fromeach rovibrational state.