Drying layer near a weakly attractive surface

Depletion of the liquid density near a solid surface with a weak longrange fluid-surface interaction was studied by computer simulations of the liquidvapor coexistence of a LJ fluid confined in slitlike pores. In a wide temperature range the liquid density decreases towards the surface without the formation of a vapor layer between the liquid and the solid surface. This evidences the absence of a drying transition up to the liquid-vapor critical point. Two contributions to the excess desorption Γtot were found. The first one Γξ ∼ ρbulk ξ exists at any temperature and diverges as the bulk correlation length ξ when approaching the liquid-vapor critical temperature Tc. The second contribution ΓL ∼ ρbulk L0 originates from a microscopic drying layer near the solid boundary. At high temperatures the thickness L0 of the drying layer increases in accordance with the power law L0 ∼ ln (1-T/Tc), indicating a drying transition at Tc. The drying layer can be suppressed by strengthening the fluidsurface interaction, by increasing the fluid-surface interaction range or by decreasing the pore size. PACS numbers: 05.70.Jk, 64.70.Fx, 68.08.Bc Drying layer near a weakly attractive surface 2