Classical Trajectory Study of HF Desorption on LiF(001) Surface

Abstract

We report a classical trajectory study of the molecular desorption of a vibrationaly 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 calculation of the gas molecule/surface interaction potential is first presented. By applying this potential, Hamilton's equations of motion can be numerically integrated with the initial conditions selected, thus the dynamics is simulated. The result gives a clear indication about the features of the evolution of the vibrational, rotational and translational energies with increase of time. The angular momentum and translational energy distributions of the desorbed molecule are presented. Desorption probabilities for different initial states of the adsorbed molecule are also predicted, which are influenced by the polar‐angle‐dependent potential and the excitation of the initial vibrational level. The surface phonon mode is found to be strongly coupled to the vibrational, rotational, translational modes of the molecule and surface bond.