POWER-LAW SCATTERING IN FLUIDS WITH A NONSCALAR ORDER PARAMETER

We studied the coarsening behavior of two lyotropic liquid-crystal sys tems by static light scattering. The samples were quenched from the is otropic phase into either the nematic phase or a region of coexistence between nematic and isotropic phases. In the coexistence region, we o bserved, in both two and three dimensions, Porod power-law tails of th e scattering intensity. Such a behavior is described by S(q) is simila r to q-(d + 1) in the limit of large wave vectors q, where S is the sc attering intensity, q is the wave vector, and d is the dimension of th e system. In addition, the nematic phases displayed novel power-law sc aling behavior at large q, namely, S(q) is similar to q(-u), where u = 4 in two dimensions and u = 6 in three dimensions. These results will be compared to recent theoretical predictions.