ARRHENIUS PARAMETERS FOR THE REACTION OF H-ATOMS WITH SIH4

The reaction H + SiH4 has been studied at 298-636 K in pulsed photolys is experiments with H atoms produced by the mercury-sensitised photoly sis of H-2 and detected by Lyman-alpha absorption. The rate constants obtained are given by k(1)/cm(3) s(-1) = (7.49 +/- 0.49) x 10(-11) exp [(-1610 +/- 25)/T] Combination of our results with previously reported data gives k(1)/cm(3) s(-1) = (1.37 +/- 0.03) x 10(-10) exp[(-1820 +/ - 10)/T] for the temperature range 290-636 K. Simulation of the observ ed dependence of the measured pseudo-first-order rate constant on the H atom concentration at 298 K and 500 Torr yields k(2) = (4.3 +/- 1.0) x 10(-11) cm(3) s(-1) for the rate constant of the atom-radical react ion, H + SiH3.