THE HNCO- VUV-PHOTOLYSIS OF THE CYANATO RADICAL VIA RYDBERG STATES(F REACTION SYSTEM )

The VUV-photolysis of the cyanato radical, NCO, formed in the reaction of isocyanic acid with fluorine atoms, leads to the formation of elec tronically excited CN fragments in the B-state. Excitation spectra in the range 105-200 nm and dispersed fluorescence spectra at selected wa velengths show that CN(B-2 Sigma(+)) fragments are formed below lambda (ex) = 145 +/- 1 nm. These spectra provide the first information on so me properties of the excited states of the NCO radical above 6.5 eV, r esulting in the tentative assignment of a ns-Rydberg series. It is pro posed that the first member, 3s, gives rise to dissociation from a ben t state, while the second member, 4s, and probably all higher members are governed by linear dissociative configurations. A vibrational prog ression in the v(1)-mode is superimposed on the 4s Rydberg transition.