CRITICAL-BEHAVIOR AT THE NEMATIC TO LAMELLAR PHASE-TRANSITIONS - A SYNCHROTRON X-RAY-SCATTERING STUDY

The nematic (N) to lamellar (L-alpha) phase transition in binary mixtu res of cesium-perfluoro-octanoate (CsPFO) and water has been studied b y high-resolution synchrotron x-ray scattering at 46.6 weight % CsPFO. The longitudinal correlation length xi(parallel to) and the susceptib ility sigma associated with the lamellar phase fluctuations in the N p hase, measured over three decades of reduced temperature, diverge with critical exponents nu(parallel to) = 0.86 +/- 0.04 and gamma = 1.37 /- 0.11, respectively. These results show that the N to L-alpha phase transition is quantitatively similar to the N to smectic-A phase trans ition of thermotropic liquid crystals with a wider nematic range.