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Measurements of the intensity and spectrum of light scattered by bend mode director fluctuations near the smectic-A to nematic phase transition of cyanobenzylidene octyloxyaniline are presented and analyzed. The longitudinal correlation length in the nematic phase appears to diverge (T- T)-0.75 and the data are consistent with the jähnig-Brochard scalilng function up to q∥ = 10. The bend viscosity diverges as (T - T) -0.5 when correction for beckground and Arrhenius temperature dependence are included.

A high-resolution calorimetric study of methylbutylphenyloctyloxybiphenyl carboxylate (8OSI) has been carried out near the smectic-C to hexatic smectic-I transition. The excess heat capacity peak ΔCl, is large but clearly rounded over a 300 mK range. The ΔCp data and previously published Co order parameter data can be fit simultaneously using a phenomenological equation of state with a temperature independent tilt field H. Interpretation of the underlying effective critical exponents α = 0.47 and β = 0.077 is not clear, but one possibility is that the SmC-SmI transition in the limit H → 0 would be weakly first-order.

Some recent experiements that have been carried out at M.I.T. provide results that illustrate the effect of thermal fluctuations on order-disorder phase transitions.

We report birefringence measurements of the nematic order parameter of the lyotropic liquid crystal formed by aqueous solution of cesium perfluoro-octanoate (CsPFO). For a mole fraction x = 0.035 of CsPFO the first order jump at the nematic-isotropic transition is about twice that in a sample with x = 0.025. The results are analyzed using a Landau-de Gennes model.

We measured the intensity and the spectrum of light scattered by the nematic liquid crystal p-methoxybenzylidene p-n-butylaniline as a function of temperature. The measurements yield the temperature dependence of the amplitude and dynamics of orientational fluctuations in the ordered phase. We analyze the results in terms of the two theories of normal modes of liquid crystals, and examine the extensions required to make the macroscopic elastic theory consistent with experiment.