A MOLECULAR THEORY OF SOLVATION FORCE OSCILLATIONS IN NONPOLAR LIQUIDS

A molecular theory based on the nonlocal density functional theory is used to calculate the solvation-force oscillations in nonpolar liquids observed with an atomic-force microscope (AFM) and a surface-force ap paratus (SFA) operated within liquid. The fluid-fluid as well as wall- fluid interactions are represented by a Lennard-Jones type potential, whose parameters are related to the Hamaker constant, The density func tional calculation shows that a stronger wall-fluid than fluid-fluid i nteraction is necessary to observe this solvation-force oscillation. T he magnitude of the Hamaker constants of various nonpolar organic liqu ids and various substrates shows that this criterion for the observati on of oscillation is normally satisfied. (C) 1998 Academic Press.