CLASSICAL TRAJECTORY STUDY OF HF DESORPTION ON LIF(001) SURFACE

We report a classical trajectory study of the molecular desorption of a vibrationally excited HF adsorbed on a corrugated LiF(001) surface. The desorption is induced by either a vibrational deexcitation of the adsorbed molecule (vibrational desorption) or an active motion of the surface ion (thermal desorption). A brief description of the calculati on of the gas molecule/surface interaction potential is first presente d. By applying this potential, Hamilton's equations of motion can be n umerically integrated with the initial conditions selected, thus the d ynamics is simulated. The result gives a clear indication about the fe atures of the evolution of the vibrational, rotational and translation al energies with increase of time. The angular momentum and translatio nal energy distributions of the desorbed molecule are presented. Desor ption probabilities for different initial states of the adsorbed molec ule are also predicted, which are influenced by the polar-angle-depend ent potential and the excitation of the initial vibrational level. The surface phonon mode is found to be strongly coupled to the vibrationa l, rotational, translational modes of the molecule and surface bond.