Effective Shape and Dynamics of Chlorophyll a in a Nematic Liquid Crystal

The ordering matrix and the three rotational diffusion tensor components of chlorophyll a dissolved in the nematic liquid crystal ZLI-1167 have been determined at various temperatures employing a time-dependent fluorescence depolarization technique. The axis normal to the porphyrin ring is aligned on average perpendicular to the director and exhibits the slowest tumbling with respect to the director. The phytyl chain tends to be aligned with the director, and its overall spinning is the fastest.