H-atom high-n Rydberg time-of-flight spectroscopy of C-H bond fission in acrolein dissociated at 193 nm

The experiments presented in this work use H-atom high-n Rydberg time-of-flight spectroscopy to measure the H-atom velocity distribution from one- and multiple-photon dissociation processes in acrolein following excitation at 193 nm. The one-photon H-atom signal is dominated by primary C-H bond fission in acrolein. We compare some of the qualitative features of the recoil translational energy distribution for the observed H atoms with what would be expected based on theoretical results for aldehydic C-H bond fission on the ground and lowest singlet and triplet excited states and conclude that the dissociation cannot proceed through either of these paths. A possible dissociation mechanism is proposed to account for the observed P(E-T) that is consistent with the observation of an isotropic dissociation. Finally, we report results on methyl vinyl ketone photodissociation which provide evidence that the primary C-H bond fission process in acrolein is fission of the aldehydic bond. (C) 2002 American Institute of Physics.