Forces between a rigid probe particle and a liquid interface: III. Extraction of the planar half-space interaction energy E(D)

Abstract

The deformation of a liquid drop (radius R0) under the probe particle (radius a) greatly complicates the interpretation by atomic force microscopy. For rigid interfaces, F(ΔX) can be directly related to the interaction energy E(D) per unit area between planar half-spaces of probe material and drop material across a thickness D of the liquid medium by the Derjaguin approximation, F(ΔX0+D0)=2π/(1/a+1/ R0)E(D0), where D0 is the intersurface separation distance on the line of the centers of the bodies and ΔX 0 is a constant set by the somewhat arbitrary choice of origin for the separation distance ΔX between the stage on which the drop rests and the lowest point on the probe particle. The proble..