| Abstrakt: |
Experimental characterization of the dynamics of multicomponent fluids is a problem of general importance to the field of complex fluids. We demonstrate a new experimental approach, termed two-color Fourier imaging correlation spectroscopy, which allows direct measurement of the partial dynamic structure factors, S11(k,τ), S22(k,τ), and S12(k,τ), where 1, 2 label the component species of a binary colloidal suspension. Linear combinations of the partial dynamic structure factors yield the characteristic time-correlation functions of the binary fluid. These are the correlation functions of concentration fluctuations SCC(k,τ), number density fluctuations SNN(k,τ), and cross-correlations between number density and concentration fluctuations SNC(k,τ). Test measurements are performed on a dilute symmetric mixture of fluorescently labeled 0.5 and 1.0 μm polystyrene spheres. From these data, we determine generalized collective and relative diffusion coefficients, and compare them to the predictions for an ideal mixture of noninteracting particles. [ABSTRACT FROM AUTHOR] |
