Knowledge Bank

Laser induced fluorescence spectra of the BaNC free radical in a supersonic jet have been recorded for the first time. A strong and rather complicated excitation spectrum was observed between $18000-19500cm-1$. A partial assignment has been made but uncertainties remain. In the corresponding dispersed fluorescence spectra, long progressions in the bending mode have been identified. The low frequency of this mode, $70cm-1$ for the fundamental, demonstrates that BaNC is relatively floppy in the bending coordinate in its ground electronic state. The intensity profiles of the bending progressions suggest that BaNC undergoes a substantial change in its equilibrium bond angle on electronic excitation. This is most likely due to formation of a bent structure in the excited electronic state.