Kinetics of C2 (a3Πu) radical reactions with NO, N2O,O2, H2 and NH3

Pulsed laser photolysis/laser-induced fluorescence (LP-LIF) is utilized to measure rate constants for C-2(a(3)Pi(u)) reactions with NO, N2O, O-2, H-2 and NH3. Multiphoton dissociation Of C2Cl4 at 266 nm is employed for the generation Of C-2(a(3)Pi(u)) radicals. The C-2(a(3)Pi(u)) concentration is monitored by the fluorescence of the (0, 0) band of the (d(3)Pi(g)<---->a(3)Pi(u)) transition at 516.5 nm. C-2(a(3)Pi(u)) removal rate constants for the reactions are determined as k(NO) = (5.46+/-0.10) x 10(-11) cm(3) molecule(-1) s(-1), k(N2O) = (1.63+/-0.20) x 10(-13) cm(3) molecule(-1) s(-1), k(N2O) = (1.58+/-0.16) x 10(-11) cm(3) molecule(-1) s(-1), k(O2) = (5.92 +/-1.00) x 10(-14) cm(3) molecule(-1) s(-1), k(H2) < 1.0 x 10(-14) cm(3) molecule(-1) s(-1). Based on the data analysis and theoretical calculation, we suggest that the C-2(a(3)Pi(u)) reactions with H-2 and NH3 proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions Of C-2(a(3)Pi(u)) with H-2 and NH3.