Power-law scattering in fluids with a nonscalar order parameter

We studied the coarsening behavior of two lyotropic liquid-crystal systems by static light scattering. The samples were quenched from the isotropic phase into either the nematic phase or a region of coexistence between nematic and isotropic phases. In the coexistence region, we observed, in both two and three dimensions, Porod power-law tails of the scattering intensity. Such a behavior is described by S(q)∼${\mathit{q}}^{\mathrm{-}(\mathit{d}+1)}$ in the limit of large wave vectors q, where S is the scattering intensity, q is the wave vector, and d is the dimension of the system. In addition, the nematic phases displayed novel power-law scaling behavior at large q, namely, S(q)∼${\mathit{q}}^{\mathrm{-}\mathit{u}}$, where u=4 in two dimensions and u=6 in three dimensions. These results will be compared to recent theoretical predictions.