MICROSCOPIC MODEL OF ASSOCIATIVE DESORPTION FOR HYDROGEN ON Mo(110)

Adsorbed hydrogen layers on the Mo(110) surface have been investigated both experimentally by temperature programmed desorption (TPD) method and theoretically by means of DFT-based optimization of surface structures. We suggest a novel microscopic model of the associative hydrogen desorption, which explains essential features of the process. In this model, the process of hydrogen desorption can be described as association of hydrogen atoms on the surface, but molecular formation is actually accomplished while the molecule moves away from the surface. We also suggest a new algorithm for realistic Monte Carlo simulations of associative desorption, which implements the microscopic description of the association of hydrogen adatoms into a molecule with activation energy, found from the DFT calculations. Good agreement between simulated and experimental TPD spectra gives insight into different behavior of the spectra, obtained for low and high hydrogen coverages on the Mo(110) surface.