ROTATIONAL DIFFUSION OF BIAXIAL PROBES IN BIAXIAL LIQUID-CRYSTAL PHASES

We present and solve for the first time the rotational diffusion equation for an asymmetric probe reorienting in a medium of biaxial symmetry. We calculate first- and second-rank correlation functions for a prolate and an oblate biaxial probe both in the uniaxial phase and the biaxial phase, which then let us investigate the evolution of the dynamic observables of interest (e.g., correlation times, second-rank spectral densities, and band shapes of dipole relaxation) through the uniaxial-biaxial phase transition. We also present results for different values of the asymmetry parameter of the molecular diffusion tenser.