T. Kammler et al., THE ROLE OF STICKING AND REACTION PROBABILITIES IN HOT-ATOM MEDIATED ABSTRACTION REACTIONS OF D ON METAL-SURFACES BY GASEOUS H-ATOMS, The Journal of chemical physics, 109(10), 1998, pp. 4071-4077
Recent experiments on the abstraction of D adsorbed on metal surfaces
with gaseous hydrogen atoms revealed a kinetics of HD formation which
is not compatible with the operation of Eley-Rideal (ER) mechanisms. F
urthermore, homonuclear products were observed during abstraction, whi
ch are not expected through an ER reaction scheme. It was therefore su
ggested that hot-atom (HA) mechanisms are more appropriate to explain
the measured kinetics and products. Random walk calculations of the ab
straction kinetics are presented based on a model which exclusively re
lies on elementary reaction steps which are HA mediated processes. Wit
hin this model, the ratio of two variables, the probabilities for hot-
atom sticking at empty sites p(s) and hot-atom reaction with adsorbed
species p(r), was found to control the kinetics of HD and D-2 formatio
n. The essential features of measured kinetic data at Ni(100), Pt(lll)
, and Cu(lll) surfaces were reproduced by simple and reasonable assump
tions on p(s)/p(r). (C) 1998 American Institute of Physics. [S0021-960
6(98)70334-4].