C. Even

Macroscopic 2D Wigner islands

In this paper we present new versatile 2D macroscopic Wigner islands useful to investigate the various behaviors observed in mesoscopic confined systems. Our Wigner islands consist of electrostatically interacting charged balls with millimeter size. We have experimentally determined the ground configurations for systems of N confined particles (N = 1-30) and checked the influence of the confinement and interacting potentials. The results obtained are compared with the published numerical results.

New Faceting Phenomena in Lyotropic Liquid Crystals

ABSTRACT In lyotropic systems, four different isotropic phases may coexist with several cubic phases having different topologies and/or symmetries. We review here faceting phenomena, rising new conceptual issues, that have been recently found to occur at different cubic/isotropic interfaces: 1°- depending on their tension, these interfaces can be either rich or poor in facets or even completely rough, 2°- when facets coexist with rough surfaces, facets can grow due to the redistribution of the surfactant in the crystal, 3°- upon a temperature cycling, ratchet-like growth of facets, until an elimination of rough surfaces takes place, 4°- asymmetric crystal shapes are induced by temperature gradients, 5°-rough surfaces “melt” prior to facets that stay “dry”.

Vibrations of smectic films

Abstract We examine the vibration spectrum of smectic films both experimentally and theoretically. We show that the main energies involved in the dynamics are the capillarity, the stretching energy, when the films are curved, and the viscous dissipation between layers. We propose a theoretical treatment of the resonance spectrum for the family of the catenoid. When the capillarity plays the dominant role (smectic A or smectic C phase), there exists a continuous family of isospectral surfaces. When the film has some elasticity (smectic B phase), we predict a deviation of the resonances governed by the Gaussian curvature.

Vibrations of smectic films on isospectral drums

Transverse stationary waves in a membrane occur for a discrete spectrum of eigenfrequencies. Two different shapes can give the same spectrum, which we have tested experimentally, using smectic films.