LIGHT-SCATTERING-STUDIES OF SURFACE VISCOELASTICITY - DIRECT DATA-ANALYSIS

Light scattering from thermally excited capillary waves can be used to study the viscoelasticity of molecular films on liquid surfaces. In particular, two surface elastic moduli and two surface viscosities affect the spectrum of the scattered light. An ab initio method of analyzing observed photon correlation functions directly in terms of these surface properties, without extraneous assumptions, is described. Typical data, both experimental and simulated, are analyzed, the discussion centering on the uniqueness and stability of the solution found by this direct analysis procedure. The limitations of the approach appear to be those intrinsic to the varying sensitivity of the capillary waves to the various surface properties. © 1990, American Chemical Society. All rights reserved.