Investigation of bulk and surface melting from microscopic view point

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Although melting transition is commonly observable in our dairy lives, the understanding of melting is still an open question in the microscopic point of view. Since anharmonic vibration plays an essential role, the EXAFS (extended x-ray-absorption fine structure) spectroscopy is useful to investigate the melting phenomenon from the view point of local structure and anharmonic vibration. In this work, we have first of all examined thermal properties of bulk materials at low temperature using EXAFS by estimating interatomic potentials with the quantum statistical approach. Here the path-integral effective-potential (PIEP) method was employed. In order to apply the PIEP method to metals, the embedded atom method was formulated and combined. In experiments, we have developed new ultrahigh vacuum chmaber for surface EXAPS measurements from low to high temperatures. We have investigated anisotropic anharmonic surface vibrations of ultrathin epitaxial flims such as KBr on KCl and Ni and Cu on graphite by means of temperature-dependent EXAFS measurements.