The HNCO + F reaction system: VUV-photolysis of the cyanato radical via Rydberg states

The VUV-photolysis of the cyanato radical, NCO, formed in the reaction of isocyanic acid with fluorine atoms, leads to the formation of electronically excited CN fragments in the B-state. Excitation spectra in the range 105–200 nm and dispersed fluorescence spectra at selected wavelengths show that CN(B2Σ+) fragments are formed below λrmex = 145 ± 1 nm. These spectra provide the first information on some properties of the excited states of the NCO radical above 6.5 eV, resulting in the tentative assignment of a ns-Rydberg series. It is proposed that the first member, 3s, gives rise to dissociation from a bent state, while the second member, 4s, and probably all higher members are governed by linear dissociative configurations. A vibrational progression in the ν1-mode is superimposed on the 4s Rydberg transition.