A MONTE-CARLO APPROACH TO TEMPERATURE PROGRAMMED REACTIVE DESORPTION - THE CASE OF H2O ON POLYCRYSTALLINE PD FILMS

A Monte Carlo model for the simulation of temperature programmed reactive desorption is developed. The model takes into account effects of adsorbate-adsorbate interaction on the desorption energy and on the activation energy for the reaction, as well as surface heterogeneity. Its potentiality is shown in discussing the case of reactive desorption of H2O from polycrystalline Pd films, where the presence of adsorbed oxygen affects the activation energy for the reaction 2OH --> H2O + O. Similarly, literature data on reactive desorption spectra of D2O in Pd(100) with various O2 precoverages were also successfully fitted with comparable adsorbate-adsorbate interaction energies.