X-ray photon correlation spectroscopy studies of colloidal diffusion and the capillary modes of polymer films

초록

The new method of X-ray photon correlation spectroscopy (XPCS) is introduced with reference to experiments studying diffusion in concentrated colloidal suspensions. It is shown that both the static structure and the diffusional dynamics of concentrated suspensions of polystyrene spheres in glycerol are well-described by theories developed for hard spheres. Next, XPCS experiments probing the dynamics of surface height fluctuations as a function of lateral length scale are described. Measurements were performed on polystyrene (PS) thin films of thicknesses varying from 840 to 3330 Angstrom at temperatures above the PS glass transition temperature. Within a range of wave vectors spanning 10(-4)-10(-3) Angstrom(-1), good agreement is found between the measured surface dynamics and the theory of overdamped thermal capillary waves on thin films. Quantitatively, the data can be accounted for using the viscosity of bulk PS. (C) 2003 Elsevier Science B.V. All rights reserved.

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