Molecular simulation of the desorption process on solid surfaces under vacuum and supercritical conditions

The applicability of molecular dynamics (MD) and computer graphics (CG) methods to investigating the dynamics of isolated adsorbed species on a MgO(001) surface under vacuum and supercritical conditions was demonstrated. The migration process of the adsorbed species was greatly affected by the morphology of the MgO(001) surface, and the desorption process of the adsorbed species was influenced by the thermal vibration of atoms of the MgO(001) surface under the vacuum condition. The supercritical extraction process from the MgO(001) surface could be reproduced by the MD simulation. In the co-existence of supercritical fluids, the desorption of adsorbed species occurred at lower temperatures compared to the situation under the vacuum condition. Furthermore, we clarified that the collision of the supercritical fluid with the adsorbed species has a significant role on the mechanism of the supercritical extraction process.