State-resolved translation energy distributions for NCO photodissociation

The photodissociation dynamics of NCO have been examined using fast beam photofragment translational spectroscopy. Excitation of the 10 , 30 , and 10 30 2 transitions of the B̃ 2P←X̃ P band produces N(S)1CO photofragments exclusively, while excitation of the 10 30 3 transition yields primarily N(D)1CO photoproducts. The translational energy @P(ET)# distributions yield D0~N–CO!52.3460.03 eV, and DH f ,0 0 ~NCO!51.3660.03 eV. The P(ET) distributions exhibit vibrationally resolved structure reflecting the vibrational and rotational distributions of the CO product. The N(D)1CO distribution can be fit by phase space theory ~PST!, while the higher degree of CO rotational excitation for N(S)1CO products implies that NCO passes through a bent geometry upon dissociation. The P(ET) distributions suggest that when the B̃ 2P←X̃ P band is excited, NCO undergoes internal conversion to its ground electronic state prior to dissociation. Excitation of NCO at 193 nm clearly leads to the production of N(D)1CO fragments. While conclusive evidence for the higher energy O(P)1CN(X S) channel was not observed, the presence of this dissociation pathway could not be excluded. © 2001 American Institute of Physics. @DOI: 10.1063/1.1369132#