RIPPLON INTERACTION BETWEEN 2 LIQUID SURFACES

The interaction between two liquid surfaces plays a central role in aerosol microphysics and liquid-drop aggregation phenomena. We study the ripplon (quantized capillary-tension waves) contribution to the interaction energy between two parallel planar liquid surfaces. For He-4 and separations between both liquid surfaces greater-than-or-similar-to 10 angstrom, the effect of ripplon excitation is negligible (smaller than 10(-3)) compared with the van der Waals energy corresponding to two flat liquid He-4 surfaces. At smaller separation distances, the ripplon contribution to the interaction energy can no longer be considered as a perturbation and it should be included in any detailed analysis of liquid-liquid interactions.