CO2 photodissociation, 1060–1175 Å

The relative O(¹S) quantum yield from CO₂ photolysis between 1060 Å and 1175 Å has been measured, to sort out the discrepancies between two prior publications on the subject. Whereas the yield is near unity over a considerable portion of the spectral regions, there is an abrupt dip to ${\phi }_{\mathrm{O}{(}^1\mathrm{S)}}\text{⩽0.15,}$ centered at 1089 Å. As this wavelength is also the location of a very strong Rydberg transiton in CO₂, it appears that the low quantum yield is associated with excitation of the upper level of this transition, the ${}^1{\Pi }_u$ state. The O(¹D) yield at this wavelength was found to have a minimum value of 0.65±0.1. In conjunction with the lack of any observable fluorescence it is concluded that dissociation on the O(¹S)+CO and O(¹D)+CO surfaces probably accounts for all the input energy.