Auto-correlation Function Analysis of Scattered Light Intensity at Different Scattering Angles

摘要

In this work, the effects of the scattering angle on the nonexponentiality ofthe normalized time auto-correlation function of the scattered light intensity$g^{(2)}(\tau) $ are investigated using dilute Poly($N$-isopropylacrylamide)microgel and standard polystyrene latex samples in dispersion respectively. Theresults show that the influences of the scattering angle on the deviationbetween an exponentiality and $% g^{(2)}(\tau) $ are small. With the assistanceof the simulated data of $g^{(2)}(\tau) $, the effects of the particle sizedistribution and scattering angle on the deviation between an exponentialityand $g^{(2)}(\tau) $ are explored. The analysis reveals that thenonexponentiality of $% g^{(2)}(\tau) $ is determined by the particle sizedistribution and scattering angle. In general, the influences of the particlesize distribution are small on the nonexponentiality of $g^{(2)}(\tau) $ andvery large on the initial slope of the logarithm of $g^{(2)}(\tau) $ and theeffects of the scattering angle are determined by the particle sizedistribution and mean particle size. Under some conditions, the deviationbetween an exponentiality and $g^{(2)}(\tau) $ is greatly influenced by thescattering angle. The values of the apparent hydrodynamic radius are alsodetermined by the particle size distribution and scattering angle. The apparenthydrodynamic radius and its distribution obtained using the cumulants methodare different from the hydrodynamic radius and its distribution.