Light Scattering Spectrum of a Nematic Liquid

We measured the intensity and the spectrum of light scattered by the nematic liquid crystal p-methoxybenzylidene p-n-butylaniline as a function of temperature. The measurements yield the temperature dependence of the amplitude and dynamics of orientational fluctuations in the ordered phase. We analyze the results in terms of the two theories of normal modes of liquid crystals, and examine the extensions required to make the macroscopic elastic theory consistent with experiment.