A high-resolution study of the NO3 radical produced in a supersonic jet

The 0oo vibrational band of the B2E′ ← X2A′2 transition in the jet-cooled NO3 radical has been studied at high resolution in the frequency- and time-domains. Under these cold conditions, the absorption band exhibits vibrational and rotational structure. The fluorescence decays are consistent with the previously reported fluorescence lifetime and some show superimposed quantum beats. A two-tier coupling scheme is proposed: the B2E′ ν = 0 level is vibronically coupled to vibrational levels in the A and/or X state, which are in turn coupled to ground state levels. Estimates of the pertinent coupling matrix elements and state densities are given.