The surface tension of a solid at the solid–vacuum interface, an evaluation from adsorption and wall potential calculations

A method for the evaluation of quantities that are experimentally inaccessible such as the surface tension at the solid–vacuum interface and the superficial tension of the fluid in contact with the solid is presented. The approach is based on consideration of an equilibrium of a fluid in solid capillary wherein a balance between surface and capillary forces has been replaced by conceptual alternative interfacial and centrifugal forces. This approach involves the simultaneous numerical solution one the special forms of the Gibbs equation for solid–fluid interface and a generalized Kelvin equation derived earlier. The latter equation takes into account interactions between the solid thick cylindrical wall and confined fluid, this body–body interaction potential has been primarily calculated using the Lennard-Jones (6-12) expression for the atom–atom pair potentials and expressed by hypergeometrical functions having good convergences. All numerical calculations shown here have been performed for the model graphite–argon system at 90 K. Finally, an analysis of the accuracy of the proposed method is considered.

Graphical abstractIn concept, the liquid hollow cylinder can rotate about its longitudinal axis at some constant angular velocity such that the centrifugal force due to rotary motion is able to exactly compensate the fluid surface forces cancelling them out. In this instance, the kinetic energy of rotary motion plays a role, which is equivalent to that played by the wall potential of the solid capillary.Figure optionsDownload full-size imageDownload as PowerPoint slide