NOVEL POLARIZATION DEPENDENCE IN DIFFUSING-WAVE SPECTROSCOPY OF CRYSTALLIZING COLLOIDAL SUSPENSIONS

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.