Triple-point wetting ofH2films adsorbed on silver

The wetting behavior of ${\mathrm{H}}_2$ films adsorbed on silver was studied with a quartz-crystal microbalance. Below the triple-point temperature $T_t$, incomplete-wetting films are observed, while above it the liquid films completely wet the substrate. Within the experimental resolution the wetting transition occurs at $T_t$. The maximum frequency change at saturation (which corresponds to the film thickness at saturation) increases as the temperature approaches $T_t$, obeying a power law of the form Δ$f_0$∝$t^{\mathrm{-}1/n}$, with n=3.28±0.3 and t=($T_t$-T)/$T_t$. The shape of the isotherms suggests the presence of two-phase films above and below the triple point.