Wetting transitions of liquid hydrogen films

Calculations are presented in the wetting properties of liquid hydrogen films on various substrates. The well depth D for the adsorption potential is even smaller for alkali metal substrates than for noble gas surfaces. A simple model calculation leads to the prediction that wetting transitions should then occur at a temperature ${\mathit{T}}_{\mathit{w}}$ about 20 K. Quartz microbalance data obtained for ${\mathrm{H}}_2$ on Rb are consistent with this result. Specifically, ${\mathit{T}}_{\mathit{w}}$ is found to be 17.89±0.04 K. The wetting phase diagram is found to be in good agreement with thermodynamic expectations.