High-resolution x-ray study of a second-order nematic-smectic-a phase transition

Abstract

We have carried out a high-resolution x-ray-scattering study of the critical fluctuations in the nematic phase associated with the nematic-smectic-A transition in N-p-cyanobenzylidene-p-octyloxyanilene (CBOOA). It is shown that for 8×10-5TTc-12×10-2 the transverse and longitudinal correlation lengths diverge with identical exponents, that is, |νL-νT|<0.03. As one approaches Tc the system appears to crossover from helium- to mean-field critical behavior at a reduced temperature of ∼10-3. © 1977 The American Physical Society.