Nature of the smectic-A-hexatic-B-crystal-E transitions in extremely thin films determined by optical reflectivity measurements

Employing high-resolution optical reflectivity measurements, we have investigated the nature of the smectic-A-hexatic-B-crystal-E transitions in extremely thin n-alkyl-4'-n-alkoxybiphenyl-4-carboxylate (nmOBC) films. The reflectivity data are shown to yield quantitative information on the molecular density of the films. The experimental technique has been found to be extremely powerful in establishing the continuous nature of the smectic-A-hexatic-B transition.