Temperature dependence of the refractive index near the reentrant-isotropic-calamitic-nematic phase transition - art. no. 012701

The laser-induced nonlinear optical response of a lyotropic liquid crystal system in the reentrant-isotropic and calamitic-nematic phases is investiga ted by the use of the thermal lens technique. The occurrence of an inversio n in the temperature coefficient of the ordinary refractive index, dn(perpe ndicular to)/dT, near the reentrant-isotropic-calamitic-nematic phase trans ition, is discussed. This effect is attributed to the behavior of the elect ronic polarizability due to the change in micelle shape near the isotropic- nematic transition, and correlated with the results obtained near the nemat ic-isotropic transition, previously reported.