Experimental comparison between microscopic energy dissipation and inelastic molecular scattering from surfaces

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The purpose of this study is to experimentally compare the microscopic mechanical energy dissipation during the observation with a non-contact atomic force microscope(nc-AFM) and the feature of the inelastic scattering of molecules from surfaces, and eventually to clarify the origin of the microscopic energy dissipation, which can be utilized to locally control the surface chemical reaction.The microscopic mechanical energy dissipations on a carbon material-partially deposited Pt(111) surface are successfully evaluated with a nc-AFM equipped with an amplitude stabilized catilever excitation by automatically compensating the contact potential difference between tip and sample surfaces which induces electric energy dissipation.On the other hand, for the evaluation of the energy dissipation with molecular beam scattering techniques, the highly oriented monolayer graphite (MG)-covered Pt(111) surface is prepared by a supersonic methane beam irradiation. The angular and velocity distributions of supersonic Ne,Ar,methane and ethane molecules scattered from clean and MG-covered Pt(111) surfaces are well explained within the framework of the classical hard cube model unless the rotational states of molecules are excited during scattering. This suggests that the contrast of the microscopic energy dissipation distribution image is due to the difference in the effective mass of the surface materials. However, the absolute values of the energy dissipations obtained from two methods are found to be largely different. The theoretical study is required to quantitatively clarify the origin of the microscopic energy dissipation.