THE COLLISIONAL BEHAVIOR OF GROUND-STATE ATOMIC CARBON, C(2P2(3PJ), WITH ETHYLENE AND ACETYLENE INVESTIGATED BY TIME-RESOLVED ATOMIC RESONANCE-ABSORPTION SPECTROSCOPY IN THE VACUUM ULTRAVIOLET

We present a kinetic study of the collisional behaviour of ground state atomic carbon, C(2p2(P-2(J))), with the molecules C3O2, C2H4 and C2H2. Atomic carbon was generated by the repetitive pulsed irradiation (lambda > ca. 160 nm) of C3O2 in a slow flow system and then monitored photoelectrically by time-resolved atomic resonance absorption in vacuum ultraviolet (lambda = 166 nm, 3P-3(J) <-- 2P-3(J)) with direct computer interfacing for data capture and analysis. The following absolute second-order rate constants for the reactions of C(2P-3(J) with the molecules C3O2, C2H4 and C2H2 were obtained: k(R)/cm3 molecule-1 s-1 (300 K); C3O2(1.8 +/- 0.1) x 10(-10), C2H4(2.0 +/- 0.1) x 10(-10) and C2H4(2.1 +/- 0.1) X 10(-10). The result for C3O2 is in accord with earlier measurements. Those for C2H4 and C2H2 yield values at least six orders of magnitude faster than initial estimates from earlier indirect measurements on a flow system.