Structure and vibrational modes of the cyanovinyl radical: A study by time-resolved Fourier transform IR emission spectroscopy

The structure and vibrational modes of the cyanovinyl radical have been characterized by using time-resolved Fourier transform IR emission spectroscopy. The cyanovinyl radical was generated with internal excitation through photodissociation of acrylonitrile. IR emission, detected with submicrosecond time resolution, from reaction products following photodissociation revealed the vibrational modes. The two vibrational modes of the cyanovinyl radical with the strongest transition strength have been identified at their fundamental transition frequencies: the CN stretch mode at 2563 cm(-1) and the CH2 out-of-plane wag at 965 cm(-1). The assignments were supported by experiments with deuterated acrylonitrile and ab initio, calculations. Rotational contour analysis of the CN emission band indicates that the equilibrium structure is bent at the CCC angle.