THEORY OF LIGHT-SCATTERING BY THIN NEMATIC LIQUID-CRYSTAL FILMS

Light scattering by thin nematic liquid crystal films is considered. T he confinement has two important consequences. First, fluctuations wit h wave vectors not equal to the difference between the wave vectors of the scattered and the incident light ray can contribute to the scatte ring. The distribution of fluctuation wave vectors relevant to the sca ttering is peaked around this difference and has a width inversely pro portional to the film thickness. Second, only a discrete set of fluctu ation wave vectors is allowed due to restrictions imposed by the bound ary conditions. Consequently, the relaxation times of the different fl uctuation modes depend on the film thickness. It appears that the rela xation time decreases due to the confinement. In the limit of vanishin g thicknesses the relaxation time goes linearly to zero with the film thickness. The main conclusions are expected to hold qualitatively for other confined nematic systems, e.g., for nematics confined in porous media.