Thermal desorption spectra of chemisorbed atoms and molecules with lateral interactions and finite mobility: Nondissociatively adsorbed molecules

A model of thermal flash desorption of interacting chemisorbed atoms and molecules from a crystal surface is developed. The possibility of adatom diffusion along the surface is taken into account, but thermal equilibrium of the adatom system during the desorption process is not assumed. The whole range of adsorbate mobilities, including absolutely immobile species as well as adsorbates in thermal equilibrium, is investigated. The result is obtained in the form of a chain of differential equations for correlation functions of occupation numbers which is solved in various approximations. The numerical results differ from the results of previous calculations and are in better agreement with the experiments. The experimental thermal desorption spectrum of CO on W(210) is satisfactorily reproduced.