ELECTROCONVECTION IN NEMATIC LIQUID-CRYSTALS - COMPARISON BETWEEN EXPERIMENTAL RESULTS AND THE HYDRODYNAMIC MODEL

We describe experimental observations illustrating the extraordinary s ensitivity of pattern formation in electroconvection in nematic liquid crystals to changes in magnitude and sign of dynamic transport coeffi cients triggered by weak fluctuations from a lower temperature nematic -smectic A phase transition. These results are compared to predictions of a hydrodynamic model (HM). We find two patterns at onset not predi cted by HM: a rectangular pattern of short normal rolls, and, at lower temperatures, localized patterns coexisting with the subcritical stat e. (C) 1997 Elsevier Science B.V.