Influence of the rotational degrees of freedom on the initial sticking probability of water on Pt{110}-(1 x 2): A molecular dynamics study

This work focuses on a molecular dynamics (MD) study of the initial sticking probability of water on the Pt{110}-(1 x 2) surface. Previous studies of the system [T. Panczyk et al., J. Chem. Phys. 131, 064703 (2009)] led to the following conclusions: (i) adsorption of water is controlled by the efficiency of the dissipation of the initial kinetic energy during collision with the surface and (ii) the process is probably dominated by the electron-hole pair excitation mechanism. In the current work, we extend this study to understand the influence of the orientation of the water molecule and its rotational energy on the probability of the energy exchange during collision. The simulated MD trajectories correspond to various orientations of water molecule at different rotational energies. We found that assuming the angular dependence on the probability of the energy exchange can explain the experimental results obtained using supersonic molecular beams, especially for high incident molecular beam energies. For low beam energies, dispersion of the incident kinetic energy must be incorporated into the model. These are the key factors that enable to model the experimental results on a good qualitative level. (C) 2010 American Institute of Physics. [doi:10.1063/1.3459060]