ROTATIONAL DIFFUSION OF BIAXIAL PROBES IN BIAXIAL LIQUID-CRYSTAL PHASES

We present and solve for the first time the rotational diffusion equat ion for an asymmetric probe reorienting in a medium of biaxial symmetr y. We calculate first- and second-rank correlation functions for a pro late and an oblate biaxial probe both in the uniaxial phase and the bi axial phase, which then let us investigate the evolution of the dynami c observables of interest (e.g., correlation times, second-rank spectr al densities, and band shapes of dipole relaxation) through the uniaxi al-biaxial phase transition. We also present results for different val ues of the asymmetry parameter of the molecular diffusion tenser.