STABILIZATION EFFECTS IN THE DECOMPOSITION OF FORMATE ON RU(001)

Both the transient and the isothermal decomposition of formate on Ru(0 01) have been studied using thermal desorption mass spectrometry. The formate decomposition rate, measured by monitoring the production rate of CO2, exhibits ''stabilization'' in both thermal desorption and iso thermal desorption measurements. At a constant heating rate, the therm al desorption spectrum of CO2 shifts up in peak temperature and become s progressively more narrow with increasing initial coverage of surfac e formate. The isothermal decomposition rate reveals a convex paraboli c curve with time prior to passing through a maximum. A simple mean-fi eld kinetic model is used to describe both the transient thermal desor ption and the isothermal desorption spectra. The stabilization kinetic s are attributed both to attractive interactions between formates as w ell as between a formate and its chemisorbed decomposition product, CO . Calculations using the mean-field model quantitatively reproduce the experimentally observed kinetic behavior.