Primary Products and Branching Ratios for Combustion Multi-Channel Bimolecular Reactions from Crossed Molecular Beam Studies

The identification of the primary products and the determination of their branching ratios as a function of translational energy for multi-channel elementary reactions of importance in combustion chemistry still represent a challenge for traditional kinetics experiments. However, this kind of information is central for the detailed modeling of combustion systems. In this chapter, the significant contribution provided by the crossed molecular beam (CMB) method with ‘‘universal’’ mass spectrometric detection and time-of-flight analysis is illustrated. In particular, we describe the basics of the CMB method empowered with ‘‘soft’’ electron impact ionization as recently implemented in our laboratory and report on its application to the study of the multi-channel elementary reactions of atomic oxygen with unsaturated hydrocarbons (acetylene, ethylene, and allene) and hydrocarbon radicals (methyl and allyl), which are of paramount interest in the combustion of hydrocarbons. The complementarity to kinetics studies and implications of the dynamics results for the modeling of combustion chemistry will be noted.