Correlation between asymmetric profiles in slits and standard prewetting lines

TL;DR

This study explores how asymmetric density profiles in slit geometries relate to prewetting lines in adsorption, revealing that symmetry breaking persists above wetting temperatures and correlates with prewetting phenomena.

Contribution

It establishes a correlation between asymmetric profiles in slit geometries and the end of prewetting lines, providing a new way to determine the prewetting critical temperature.

Findings

Asymmetric density profiles occur above the wetting temperature.

The disappearance of SSB correlates with the end of prewetting lines.

Asymmetry coefficients can precisely determine the prewetting critical temperature.

Abstract

The adsorption of Ar on substrates of Li is investigated within the framework of a density functional theory which includes an effective pair potential recently proposed. This approach yields good results for the surface tension of the liquid-vapor interface over the entire range of temperatures, T, from the triple point, T_t, to the critical point, T_c. The behavior of the adsorbate in the cases of a single planar wall and a slit geometry is analyzed as a function of temperature. Asymmetric density profiles are found for fluid confined in a slit built up of two identical planar walls leading to the spontaneous symmetry breaking (SSB) effect. We found that the asymmetric solutions occur even above the wetting temperature T_w in a range of average densities rho*_ssb1 <= rho*_av <= rho*_ssb2, which diminishes with increasing temperatures until its disappearance at the critical prewetting point T_cpw. In this way a correlation between the disappearance of the SSB effect and the end of prewetting lines observed in the adsorption on a one-wall planar substrate is established. In addition, it is shown that a value for T_cpw can be precisely determined by analyzing the asymmetry coefficients.