Coherencehyphen;length anisotropy above the isotropichyphen;tohyphen;nematic transition in a series of benzylidene anilines

摘要

The relative depolarized scattering strength and the coherence length anisotropy have been measured in a series ofphyphen;Nhyphen;alkoxybenzylidenephyphen;nhyphen;butylanilines with alkyl chain lengthn=1,2,4,7, and 8. All compounds appear to obey meanhyphen;field theory. The depolarized scattering strength at a given reduced temperature (Tminus;Tast;)/Tast; decreases with increasing chain length, whereas the freehyphen;energy parameterL2that characterizes the anisotropy is roughly constant. There is no apparent modification in the observed pretransitional effects when the transition changes from isotropichyphen;tohyphen;nematic (n8) to isotropichyphen;tohyphen;smectic (n=8).