The Collisional Behaviour of Ground State Atomic Carbon, C(2p2 (3PJ)), with Unsaturated Cyclic Compounds Studied by Time‐Resolved Atomic Resonance Absorption Spectroscopy in the Vacuum Ultra‐Violet

Abstract

AbstractWe present a kinetic investigation of the collisional behaviour of ground state atomic carbon, C(2p2 (3PJ)), with unsaturated cyclic compounds. Atomic carbon was generated by the repetitive pulsed irradiation (λ > ca. 160 nm) of C3O2 in the presence of excess helium buffer gas and the added reactant gases in a slow flow system, kinetically equivalent to a static system. C(23PJ) was then monitored photoelectrically by time‐resolved atomic resonance absorption in the vacuum ultra‐violet (λ = 166 nm, 33PJ←23PJ) with direct computer interfacing for data capture analysis. The following absolute second‐order rate constants for the reactions of C(23PJ) with the following cyclic collision partners are reported (errors 2σ), demonstrating rapid reaction in all cases: magnified image These results constitute the first reported body of absolute rate data for reactions of ground state carbon with these reactants. Whilst a large body of absolute rate data for atomic silicon in its Si(3p2 (3PJ)) ground state has now been determined directly in recent years by time‐resolved atomic resonance absorption spectroscopy in the ultra‐violet itself with a wide range of collision partners, including unsaturated reactants, there are no analogous data for these cyclic reactants. Comparison is made with rate data for C(23PJ) with benzenoid and fluorinated benzenoid collision partners, and the results also discussed in the context of nucleation and soot formation in flames.