ULTRALOW-TEMPERATURE KINETICS OF CH(X(2)PI) REACTIONS - RATE COEFFICIENTS FOR REACTIONS WITH O-2 AND NO (T=13-708 K), AND WITH NH3 (T=23-295 K)

The pulsed laser photolysis (PLP), laser-induced fluorescence (LIF) te chnique for the study of the kinetics of free-radical reactions is app lied to reactions of CH radicals both in the ultralow-temperature envi ronment of a Cinetique de Reaction en Ecoulement Supersonique Uniforme (CRESU) apparatus, as well as in a conventional heated cell. The comb ined techniques provide kinetic data over an extremely wide temperatur e range. Rate coefficients are reported for the reactions of CH with O -2 (T = 13-708 K), NO (T = 13-708 K), and NH3 (T = 23-295 K). All thre e reactions remain very rapid down to the lowest temperatures at which measurements were made and display differing temperature dependences. The results are discussed in the light of previous work on these syst ems and of the reaction mechanisms.