Arrhenius parameters for the reactions of H atoms with PH3 and AsH3

Rate constants for H-atom attack on PH3 and AsH3 have been measured in flash photolysis experiments in which H atoms were generated by the Hg-sensitised photolysis of H-2 and monitored by Lyman-alpha absorption. The values obtained for PH3, in the temperature range 293-472 K, are given by k(1)/cm(3) s(-1) = (1.09 +/- 0.08) x 10(-10) exp[(-1048 +/- 27)/T] and for AsH3, in the temperature range 294-424 K, by k(2)/cm(3) s(-1) = (2.57 +/- 1.30) x 10(-10) exp[(-718 +/- 160)/T] An evaluation of the available data on H + PH3 has been carried out, and the best value for the rate constant over the temperature range 200-500 K is recommended to be k(1)/cm(3) s(-1) = (0.721 +/- 0.041) x 10(-10) exp[(-887 +/- 19)/T].