On the origin of the asymmetric shape of the HCl photodissociation cross section

A first principles treatment of the photodissociation of HCl and DCl from 50 000 cm−1 to 75 000 cm−1 is presented. The treatment is the first to correctly reproduce the asymmetric absorption profile observed for HCl. The theoretical model for the HCl and DCl photodissociation presented in this study considers a dissociation process that occurs on a repulsive electronic state (A1Π) coupled to a bound electronic state (C1Π). The asymmetry in the HCl cross section arises because of the radial coupling introduced by the rotation-free nuclear kinetic energy operator.