KINETICS OF THE REACTION AL(P-2(0))+H2O OVER AN EXTENDED TEMPERATURE-RANGE

The temperature dependence of the reaction Al(P-2(0)) + H2O has been investigated over the temperature range 298-1174 K. Aluminum atoms were produced by photodissociation of Al(C2H5)3 and were detected by laser-induced fluorescence. Nonlinear Arrhenius behavior is observed, and the measured rate constants can be described by the expression k(T) = (1.9 +/- 1.5) X 10(-12) exp[-(0.88 +/- 0.44 kcal mol-1)/RT] + (1.6 +/- 0.7) X 10(-10) exp[-(5.7 +/- 0.9 kcal mol-1)/RT] cm3 s-1, where the uncertainties represent +/-2sigma. At room temperature the rate constant is pressure independent between 10 and 110 Torr total pressure (Ar buffer gas). Results are interpreted in terms of two metathesis reactions with different Arrhenius parameters, one yielding AlO and the other AlOH.