Molecular beam study of H2O interaction with Pt(111)

We have developed a highly stable supersonic H2O molecular beam and examined its properties by time-of-flight technique. A wide range of incident kinetic energy Ei of 340-730 meV with ΔE/E of 0.2-0.3 and 77-163 meV with ΔE/E of 0.4-0.6 is achieved by seeding He and He+Ar, respectively. The incident kinetic energy dependence of the angular intensity distributions of H2O scattered from Pt(111) at 500 K is measured in order to understand the inelastic scattering process of H2O on Pt(111). The comparisons of H2O scattering with Ne scattering from Pt(111) and with the prediction of the simple classical binary collision model reveal that not only phonon creation in the surface but also a large amount of H2O rotational mode excitation and/or chattering scattering takes place during collision, particularly for high incident kinetic energy conditions.