Threshold criterion for wetting at the triple point

TL;DR

This study uses simulations to analyze wetting behavior of gases on metal surfaces near the triple point, identifying a threshold wetting parameter that predicts wetting transitions.

Contribution

It introduces a threshold criterion for wetting at the triple point based on simulations and a heuristic model, extending understanding of wetting transitions.

Findings

Wetting behavior varies with system and temperature.

A wetting threshold parameter w is approximately 3.3.

Results align with previous experimental and simulation studies.

Abstract

Grand canonical simulations are used to calculate adsorption isotherms of various classical gases on alkali metal and Mg surfaces. Ab initio adsorption potentials and Lennard-Jones gas-gas interactions are used. Depending on the system, the resulting behavior can be nonwetting for all temperatures studied, complete wetting, or (in the intermediate case) exhibit a wetting transition. An unusual variety of wetting transitions at the triple point is found in the case of a specific adsorption potential of intermediate strength. The general threshold for wetting near the triple point is found to be close to that predicted with a heuristic model of Cheng et al. This same conclusion was drawn in a recent experimental and simulation study of Ar on CO_2 by Mistura et al. These results imply that a dimensionless wetting parameter w is useful for predicting whether wetting behavior is present at and above the triple temperature. The nonwetting/wetting crossover value found here is w circa 3.3.