Photolysis and spectroscopy of vibrationally excited C-H overtones of CHFCl2

Photodissociation of jet-cooled vibrationally excited CHFCl2 coupled with m ass spectroscopic detection of Cl-35 (P-2(3/2)) [Cl], Cl-35 (P-2(1/2)) [Cl* ], Cl-37 (P-2(3/2)), Cl-37 (P-2(1/2)), and H photofragments was performed. It enabled determination of Cl*/Cl and H/[Cl* + Cl] branching ratios and me asurement of the action spectra of the N = 3, N = 7/2, and N = 4 CH stretch -bend polyads. Enhanced C-Cl and C-H bond breaking was observed for all the initially prepared C-H stretch-bend states demonstrating that energy is no t preserved in the initial state but rather flows into the other part of th e molecule. The yield of Cl* photofragments was found to be about half that of Cl for similar to 235 nm photolysis of vibrationally excited CHFCl2. Th e action spectra are significantly narrower than the room-temperature photo acoustic spectra due to reduction of the rotational inhomogeneous structure . The action spectra also enabled one to resolve the components arising fro m the different isotopomers of the precursor and a resonance splitting attr ibuted to a local resonance of the 7/2(1) polyad component with a combinati on of the 7/2(3) component and the ClCCl bending. This splitting reflects a similar to 3 ps period for the vibrational redistribution and indicates th at the coupling of the stretch-bend mixed state to the rest of the molecule is weaker than the stretch-bend coupling itself.