ExoMol photodissociation cross-sections – IV. Photodissociation rates of the CH radical

ABSTRACT Photodissociation cross-sections are computed as a function of temperature for the methylidyne radical, CH. The model explicitly considers the lowest 13 electronic states of CH and are topped up at short-wavelengths using available results. The effects of predissociation due to curve crossing and tunnelling through a centrifugal barrier are both explicitly considered, alongside direct photodissociation. Photodissociation rates of CH in standard astronomical radiation fields are large but found to show only minor dependence on the temperature of the CH, in contrast to previous studies on diatomic hydrides. The SBYT cross-sections are made available via the ExoPhoto data base www.exomol.com/ExoPhoto.