Kinetic Monte Carlo modeling of CO desorption and adsorption on Pd(110) surface

Desorption and adsorption of carbon monoxide on Pd(110) is modeled and simulated, aiming at gaining atomic level understanding of experimentally observed rates. The model parameters are fitted to reproduce the temperature programmed desorption spectra and molecular beam surface scattering data. Desorption turns out to be best described as thermally activated, the activation energy depending on the detailed nearest neighbor site occupation configuration. For a good fit, the adsorption induced surface reconstruction needs to be included in the model. Also, desorption needs to be modeled with a precursor state included. However, surface diffusion was not found to be essential. With these ingredients the coverage dependent sticking coefficient can be successfully simulated in the temperature range from 300 to 500 K. Furthermore, the experimentally observed saturation coverage—temperature dependence is correctly predicted from the balance between simultaneous adsorption and desorption.