Benetzung fester und flüssiger van der Waals-Filme

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The project deals with weakly bound van der Waals films formed by molecular hydrogen and the light noble gases. Such films usually display the phenomenon of triple point wetting, i.e. complete wetting of the liquid phase above the triple point temperature Tt and incomplete wetting of the solid phase below Tt. In recent experiments we have shown that this behavior does not change qualitatively when the adsobate-substate interaction is modified by preplating the substrate with thin inert buffer layers. This result is at variance with current theory. The origin for this discrepancy is not clear: it might be due to shortcomings in the theoretical treatment, but may also be caused by the nonideal substrate surfaces used in the experiment. In order to investigate this problem the experimental results obtained here are to be analyzed in close collaboration with a theoretical project (Prof. H. Löwen) in which computer simulations will be carried out which go beyond the existing phenomenogical theory. Future adsorbate-substrate combinations to be studied will also be selected on the basis of this comparison. Moreover, emphasis will be put on the in situ preparation of well-defined substrate and their characterization in order to study the role of disorder and inhomogeneities on the wetting behavior of solid van der Waals films.