Table of contents

We discuss a model to describe the diffuse double layer of films made with ionic soap in the presence of an additional electrolytic species. The mechanism for surface charging is explained geometrically as a consequence of the hydrophobic nature of the soap anion tails. We carry out a mean-field analysis of the system, and calculate physical observables, including the electrostatic disjoining pressure isotherm for films and the surface tension of their bulk solutions. We compare the theory with experimental results and obtain good agreement across a wide range of measurements.

A random-matrix theory is presented for the reflection of light by a disordered medium backed by a phase-conjugating mirror. Two regimes are distinguished, depending on the relative magnitude of the inverse dwell time of a photon in the disordered medium and the frequency shift acquired at the mirror. The qualitatively different dependence of the reflectance on the degree of disorder in the two regimes suggests a distinctive experimental test for cancellation of phase shifts in a random medium.

Kraichnan's (J. Acoust. Soc. Am., 27 (1955) 438) formulation of the equilibrium statistical mechanics of compressible isotropic turbulence is generalized to include cases with strong excitation of individual systems. An ideal compressible finite Fourier system is shown to evolve towards an equipartition of energy between acoustic and vorticity modes in the equilibrium distribution.

Mimimizing a free-energy functional, we investigate the stability of ferroelectric fluid and various solid phases in the Stockmayer system. Our functional is based on the correlations of the isotropic fluid, calculated by integral equations. At the reduced dipole moment m* = 2.0 we found a ferroelectric fluid, but this phase is surpassed by a polarized body-centered tetragonal crystal. Moreover, the system seems to have no liquid phase at all. This behaviour changes when the strength of the isotropic attraction is increased.

The rotational dynamics of nearly spherical and cylindrical tracers dissolved in supercooled o-terphenyl is studied via the Electron Spin Resonance spectroscopy. On decreasing the temperature, a sharp crossover is observed from the regime where the Debye-Stokes-Einstein law (DSE) holds to a new one which is accounted for by a fractional DSE (FDSE) D_r ∝ (η/T)^−ξ with ξ ⩽ 1. D_r is the rotational diffusion constant, η the shear viscosity and T the temperature. Tumbling and spinning of the cylindrical tracer exhibit distinct crossovers. A simple model of FDSE based on the presence of dynamic heterogeneities is presented.

Atomic configurations of cleaved GaAs (110) surfaces are analysed to check existing models of cleavage and step formation in solids. Morphologies of 1 μm² were investigated in UHV at 300 K with a Scanning Tunneling Microscope and compared to Monte Carlo simulations. The analysis supports the view that the processes involved in fracture are far from thermal equilibrium. Two characteristic length scales are found in the morphologies. Mean terrace widths of 10 nm and large-scale fluctuations of 100 nm both point to non-linear lattice dynamic instabilities which occur during crack propagation.

We study the transport through two impurities in a one-dimensional quantum wire, taking account of long-range Coulomb interactions. We compute the temperature-dependent conductance G(T). Long-range forces lead to a dramatic increase of weak barrier potentials with decreasing temperature, even on "resonance". The system thus always reaches a "strong barrier" regime in which only the charge is pinned, contrary to the standard Luttinger liquid. G(T) vanishes faster than any power as T goes to zero. In particular, resonant tunneling is suppressed at zero temperature.

We show that weak off-diagonal disorder in degenerate ground-state conjugated polymers results in a finite density of randomly positioned kinks (solitons and antisolitons) in the lattice dimerization. For realistic values of the disorder, these kinks should clearly show up in the optical and magnetic properties.

We analyse the easy magnetisation axis "switching" recently discovered in experiments on Co ultrathin films with a deposited submonolayer of Cu by abinitio methods. The present large-scale calculations show that the nanomagnetic pattern of a stepped Co(001) surface 2-3 monolayers thick with submonolayer quantities of Cu has a complex three-dimensional character. We show that the maximum non-collinearity of spin-directions is about 30°, and the "switching" has a re-entrant character as a function of Cu coverage.