The intensity correlation function in evanescent wave scattering

Cichocki, B.; Lang, P. R.; Dhont, J. K. G.; Wajnryb, E.; Blawzdziewicz, J.

doi:10.1063/1.3305328

Journal Article

The intensity correlation function in evanescent wave scattering

Cichocki, B. ; Wajnryb, E. ; Blawzdziewicz, J. ; Dhont, J. K. G.FZJ* ; Lang, P. R.FZJ*

2010
American Institute of Physics Melville, NY

The journal of chemical physics 132, 074704 (2010) [10.1063/1.3305328]

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Please use a persistent id in citations: http://hdl.handle.net/2128/4665 doi:10.1063/1.3305328

Abstract: As a first step toward the interpretation of dynamic light scattering with evanescent illumination from suspensions of interacting spheres, in order to probe their near wall dynamics, we develop a theory for the initial slope of the intensity autocorrelation function. An expression for the first cumulant is derived that is valid for arbitrary concentrations, which generalizes a well-known expression for the short-time, wave-vector dependent collective diffusion coefficient in bulk to the case where a wall is present. Explicit expressions and numerical results for the various contributions to the initial slope are obtained within a leading order virial expansion. The dependence of the initial slope on the components of the wave vector parallel and perpendicular to the wall, as well as the dependence on the evanescent-light penetration depth are discussed. For the hydrodynamic interactions between colloids and between the wall, which are essential for a correct description of the near-interface dynamics, we include both far-field and lubrication contributions. Lubrication contributions are essential to capture the dynamics as probed in experiments with small penetration depths. Simulations have been performed to verify the theory and to estimate the extent of the concentration range where the virial expansion is valid. The computer algorithm developed for this purpose will also be of future importance for the interpretation of experiments and to develop an understanding of near-interface dynamics, at high colloid concentrations.

Keyword(s): Algorithms (MeSH) ; Colloids: chemistry (MeSH) ; Computer Simulation (MeSH) ; Diffusion (MeSH) ; Light (MeSH) ; Models, Chemical (MeSH) ; Particle Size (MeSH) ; Radiation (MeSH) ; Scattering, Radiation (MeSH) ; Spectrum Analysis (MeSH) ; Surface Properties (MeSH) ; Colloids ; J ; colloids (auto) ; diffusion (auto) ; interface phenomena (auto) ; light reflection (auto) ; light scattering (auto) ; suspensions (auto)

Classification:

Physics, Atomic, Molecular & Chemical

Note: J.B. would like to acknowledge financial support from NSF Grant Nos. CBET-0348175 and CBET-0931504. J.K.G.D. and P.R.L. acknowledge financial support by the EU-FP7 Network "NanoDirect" (Contract No. CP-FP-213948-2). B.C. acknowledges support by the Deutsche Forschungsgemeinschaft (SFB-TR6, Project No. A01).

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