CO product distributions from the visible photodissociation of HCO

The final state distribution of carbon monoxide produced in the photodissociation of the formyl (HCO) radical has been studied both experimentally and theoretically. Renner–Teller coupling between the excited HCO Ã state and the ground state leads to dissociation and yields H and CO. Vibrational and rotational distributions have been measured for CO produced after excitation to specific vibrational levels on the Ã←X̃ transition of HCO cooled in a supersonic expansion. The strongest transitions are for excitation to vibrational states with six to 16 quanta in the bending mode, and dissociation from these states produces inverted CO rotational distributions with average rotational quantum numbers