Order and dynamics of 9,10-diphenylanthracene in the liquid crystal ZLI-1167. A fluorescence depolarization study

The behavior of the probe 9,10-diphenylanthracene (DPA) dissolved in the nematic and isotropic phase of the cyanocyclohexyl mesophase mixture ZLI-1167 has been investigated using fluorescence depolarization on the nanosecond time scale. The orientational order parameters and the rotational diffusion coefficients of the fluorescent probe molecule have been determined as a function of temperature together with its fluorescence lifetimes using the Global Target Analysis method with exponential spline interpolating functions. In the isotropic phase of the liquid crystal the probe dynamics approaches the hydrodynamic behavior under slip boundary conditions. A comparison with DPA rotational diffusion times in other systems is provided.