The Bristol & Oxford Chemical Dynamics Group

Mechanisms of chemical and photochemical reactions of organic molecules in the gas and solution phases

All participating groups have programmes designed to explore (experimentally and computationally) the dynamics of gas phase bimolecular reactions and/or of isolated molecules following photoexcitation. Such studies address the fundamental processes that govern chemical reactivity. The foci of this SWP are on reactions involving polyatomic molecules (seeking to bridge the gap between chemical dynamics and the broader practice of chemistry) and on identifying thematic concepts in excited state molecular photochemistry. All of the experimental studies employ molecular beam sources and imaging (or Rydberg tagging) detection methods. Most are designed to allow comparison and contrast with the corresponding reaction occurring in a bulk liquid, with a view to learning more about the roles of solvent molecules on chemical mechanisms.

Work undertaken within the Programme Grant is intended to advance this SWP in two ways. First, it will enable in-depth experimental and theoretical studies of carefully chosen families of bimolecular (e.g. H abstraction from a range of organic molecules by reaction with F or Cl atoms, or CN radicals) or photoinduced (e.g. molecular elimination, ring-opening) reactions. Second it will introduce and demonstrate new technologies (e.g. higher resolution velocity map imaging, 'universal' detection, multimass imaging, etc) for tackling these and related problems in gas phase chemical science.

Velocities of Vibrationally excited HCl in low rotational statesin the Cl and propene reaction. The cartoon defines the scattering angle. The co-product has low internal excitation, indicated by the distribution reaching the ring that demarcates the energetic limit. This image shows that 'stripping' dynamics plays a role in Cl + alkene systems.

Contrasting images of the C2H5+, C2H3+, C2H4+ and CH2Br+ fragments from a proving multimass imaging study of the 355 nm photolysis of bromoethane cations. Multimass capability is a novel aspect of the PImMS camera.

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