Molecular beam studies of the combustion reaction of oxygen atoms with propene: Primary products, branching ratios, and role of intersystem crossing

The reactions of ground state oxygen atoms with unsaturated hydrocarbons are of central importance in combustion. We have recently investigated the O-atom reactions with acetylene, ethylene, allene and methylacetylene using the crossed beams method with universal mass spectrometric detection empowered by soft electron-ionization to characterize the dynamics of the energetically allowed channels and explore how primary products, branching ratios and extent of intersystem crossing vary with molecular complexity, electronic structure and collision energy. Here we extend the investigation to the O atom reaction with propene, which due to its larger structural complexity can serve as a gateway to the richer chemical pathways available in larger hydrocarbons. Combination of product angular and velocity distributions at different product mass-to-charge ratios enables to conclusively distinguish the various products and assign them to appropriate reaction channels. Comparisons are made with the results of recent kinetics and theoretical work.