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

Abstract

We report an unexpected behavior of the intensity autocorrelation functions C_VV(t) (polarized) and C_HH(t) (depolarized) of multiply scattered light from dense colloidal polyball crystals under certain conditions. We find that C_VV(t) saturates at large times as expected for a frozen phase, while C_HH(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.