By: Andrew Parry
From: Imperial College London, UK
At: Instituto de Investigação Interdisciplinar, Anfiteatro
We consider a structured substrate in which a tall cylinder protrudes from a flat surface. When brought into contact with a vapour close to saturation our intuition is that, for sufficiently small contact angles, a droplet of liquid will condense at the bottom of the cylinder. For systems with short-ranged forces the macroscopic dimensions of the drop show a remarkable property; the width and height are near identical to expressions for the parallel correlation length and thickness of a microscopic wetting film. The only difference is a scale factor - the role played by the microsscopic bulk correlation length is replaced by the cylinder radius. This geometrical amplication of the underlying wetting length scales is valid for critical wetting, complete wetting and first-order wetting and points to an unforeseen connection between microscopic wetting and macroscopic capillarity.