Molecular Beam Study of the Oxidation of Deuterium on a (111) Platinum Surface

Abstract

The reaction D2+12O2→D2O occurring on a (111) Pt surface has been investigated using modulated molecular beam techniques. With a molecular beam of D2 and a (111) Pt surface immersed in an O2 ambient, the production of D2O was studied as a function of D2 flux and temperature, O2 pressure, Pt temperature and the angle of incidence of the D2 beam. From these data the rate of production of D2O can be expressed by a reaction rate proportional to PD 2 2.0 PO 2 0.8 exp[−3.6 (kcal/mole) / kTD 2] exp[−12 (kcal/mole) / kTPt]in the pressure and temperature regime PD 2 ∼ 10 −7 torr, PO 2 ∼ 10 −5 torr, TD 2 ∼ 1200°K, and TPt ∼ 700°K. Further, a reaction mechanism which is consistent with this rate expression and also with the observed angular dependence is presented.