Effect of the rotational depolarization in flourescent measurements of the nematic order parameters

The effect of the rotational depolarization of the values of the order parameters <p₂ > … <p₄ > of nematic liquid crystals, determined by polarization flourescence measurements has been considered using the theory recently developed by Zannoni. For this purpose an approximate solution of the equation for the rotational diffusion in a nematic phase has been obtained in an analytical form. The order parameters of the nematic p-ethoxy-benzylidene-p-n-butylaniline have been determined experimentally and the neglect of the rotational molecular motion was found to lead to incorrect values of the order parameters.