Photodissociation of acryloyl chloride in the gas phase

The 193 nm photodissociation dynamics of CH2CHCOCl in the gas phase has been examined with the technique of time-resolved Fourier transform infrared emission (TR-FTIR) spectroscopy. Vibrationally excited photofragments of CO ( v <= 5), HCl (v <= 6), and C2H2 were observed and two photodissociation channels, the C-Cl fission channel and the HCl elimination channel have been identified. The vibrational and rotational state distributions of the photofragments CO and HCl have been acquired by analyzing their fully rotationally resolved v -> v - 1 rovibrational progressions in the emission spectra, from which it has been firmly established that the mechanism involves production of HCl via the four-center molecular elimination of CH2CHCOCl after its internal conversion from the S-1 state to the S-0 state. In addition to the dominant C-Cl bond fission along the excited S-1 state, the S-1 -> S-0 internal conversion has also been found to play an important role in the gas phase photolysis of CH2CHCOCl as manifested by the considerable yield of HCl.