Triple-point wetting of molecular hydrogen isotopes
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چکیده
Triple-point wetting is a well-known phenomenon of simple adsorbates on solid substrates, which involves, in the liquid phase above the triple-point temperature, T3, complete wetting with the formation of arbitrary thick films being observed, whereas below T3 only a few monolayers of the solid phase are adsorbed at saturated vapour pressure. This effect is usually ascribed to the substrate-induced strain in the solid film, which occurs due to the lattice mismatch and the strong van der Waals pressure in the first few monolayers. Molecular hydrogen is a suitable system in which to investigate this phenomenon, in particular by tailoring the adsorbate–substrate interaction by means of thin preplating layers of other adsorbates, and by introducing disorder into the system by using not only the pure systems H2 and D2, but also mixtures thereof. The experiments show that triple-point wetting is a rather dominant effect which, in contrast to expectations, persists even if the system parameters are widely varied. This indicates that the present understanding of this effect is incomplete. We present an investigation of the influence of the roughness of the substrate which is expected to be responsible for the dewetting of the solid phase.
منابع مشابه
Triple-point wetting on rough substrates.
The influence of substrate roughness on the wetting scenario of adsorbed van der Waals films is investigated by theory and experiment. Calculating the bending free energy penalty of a solid sheet picking up the substrate roughness, we show that a finite roughness always leads to triple-point wetting reducing the widths of the adsorbed solid films considerably as compared to that of smooth subst...
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تاریخ انتشار 2005