Novel polarization dependence in diffusing-wave spectroscopy of crystalizing colloidal suspensions

Abstract

We report an unexpected behavior of the intensity autocorrelation functions CVV(t) (polarized) and CHH(t) (depolarized) of multiply scattered light from dense colloidal polyball crystals under certain conditions. We find that CVV(t) saturates at large times as expected for a frozen phase, while CHH(t) decays to zero in a short time as in a fluid. We present a new phenomenological model for this behavior based on decoupled translational and orientational fluctuations in a weakly depolarizing medium. Our study highlights the greater sensitivity of depolarized diffusing-wave spectroscopy as a probe of the dynamics of the medium.