Combined study of structural and thermodynamic investigations of monolayer adsorbed on graphite

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The system which we dealt with in this study was the monolayer physically adsorbed on the surface of graphite. The purpose of the study was to determine the two-dimensional structure, to see the dynamics and to investigate the thermodynamic properties. In order to achieve this, X-ray/neutron diffraction, neutron scattering and measurements of the isotherm and the heat capacity were carried out.We investigated the monolayer of the following molecules ; argon, krypton, nitrogen, carbon monoxide, dinitrogen monoxide, methane (and its deuterated analogs), methyl fluoride, methyl chloride, methyl bromide, methyl iodide, neopentane (and its deuterated analog), tetramethyl tin, sulfuryl fluoride, sulfur hexafluoride, methanol (and its deuterated analogs), tert-butanol and C_<60>. Some mixtures were also investigated.We found some two-dimensional phase transitions for the monolayer of krypton, nitrogen, carbon monoxide, methane, methyl fluoride, methyl chloride, neopentane, sulfuryl fluoride and sulfur hexafluoride. The two-dimensional structure was determined for the monolayer of carbon monoxide, methane, methyl fluoride, neopentane and methanol. The rotational and vibrational states were also investigated. The rotational tunneling was investigated for the monolayer of isotopic methanes and methyl fluoride. An orientational disordered phase was found for the monolayer of some globular molecules such as neopentane, sulfuryl fluoride and sulfur hexafluoride.This study proved that the combination of the structural and thermodynamic investigations is quite effective to uncover the nature of the two-dimensional molecular solids. An international collaboration is essential to tackle with such problem systematically which has many aspect to be investigated.