Multiple source modulated molecular beam reactive scattering applied to hydrogen recombination and oxidation on the Rh(111) surface

Publisher Website
Google Scholar
Abstract
Surface kinetics which are nonlinear and involve multiple reactants are not amenable to standard modulated molecular beam reactive scattering techniques. To explore these complex reactions, we have developed a new three molecular beam arrangement. Two continuous, independently adjustable beams establish steady state surface concentrations, while a third weaker beam is modulated to induce small concentration perturbations around the selected steady state. This permits experimental linearization of nonlinear kinetics over a wide range of coverages, helping us to evaluate coverage dependent rate constants and to isolate individual elementary steps from complex reaction mechanisms. The technique has been applied to the oxidation of hydrogen to water on the Rh(111) surface. We have demonstrated linearization of the water reaction with isotopic substitution forming HDO. The analysis is illustrated by the simpler example of hydrogen–deuterium recombination. HD shows an activation energy of 20 kcal/mol and preexponential on the order of 10−2 cm2 s−1 for the linearized reaction in the low coverage limit.

This publication has 0 references indexed in Scilit: