Growth of bimolecular films of three-tailed amphiphiles.

The three-tailed amphiphile ferric stearate molecule, which forms a bimolecular layer on water surface with molecules in the lower and upper layers in different conformations, has been studied to understand transfer and growth of bimolecular films on the surface of hydrophilic silicon substrates. This bimolecular film forms a two-dimensional lattice on water with a slightly distorted hexagonal lattice where both the in-plane and out-of-plane domain sizes are small. The film also showed larger microscopic rigidity compared to its macroscopic mechanical response.

Dramatic enhancement of capillary wave fluctuations of a decorated water surface.

We have demonstrated by x-ray diffuse scattering that a bimolecular layer of a preformed three-tailed amphiphile, ferric stearate, drastically enhances capillary wave fluctuations on water surface due to a reduction in surface tension to 1 mN/m . The bimolecular layer is composed of molecules in symmetric configuration, on top of molecules in asymmetric configuration with ferric ions in contact with water. Unlike the usual Langmuir monolayers, this layer of molecules does not rupture under compression, but becomes thicker.

X-ray synchrotron study of liquid-vapor interfaces at short length scales: effect of long-range forces and bending energies.

We have investigated the small-scale structure of the liquid-vapor interface using synchrotron x-ray scattering for liquids with different molecular structures and interactions. The effective momentum-dependent surface energy first decreases from its macroscopic value due to the effect of long-range forces, and then increases with increasing wave vector. The results are analyzed using a recent density functional theory.

Reduction in the surface energy of liquid interfaces at short length scales.

Liquid-vapour interfaces, particularly those involving water, are common in both natural and artificial environments. They were first described as regions of continuous variation of density, caused by density fluctuations within the bulk phases. In contrast, the more recent capillary-wave models assumes a step-like local density profile across the liquid-vapour interface, whose width is the result of the propagation of thermally excited capillary waves.