Observation of the (A)over-tilde1A" state of isocyanogen

The A (1)A(') state of isocyanogen, CNCN, is observed using photofragment fluorescence excitation spectroscopy in a room temperature cell and in a molecular beam. The spectra are highly congested, but progressions that correspond to the Franck-Condon active C-N-C bending vibration in the excited state are evident. Linewidth measurements indicate that the excited state lifetime is < 10 ps. These measurements are consistent with previous ab initio calculations, which predicted a bent excited state with a short lifetime due to predissociation. Although we do not believe that we have observed the origin band of the electronic transition, we place an upper limit of 42 523 cm(-1) on the energy of the excited state zero point level. (c) 2007 American Institute of Physics.