Hexatic and fat-fractal structures for water droplets condensing on oil.

Abstract

Experiments on water droplets condensing on a liquid substrate (breath figures) are reported. Attractive capillary interactions between drops lead to the formation of particular two-dimensional structures. An hexatic order with exponent \ensuremath{\eta}\ensuremath{\approxeq}0.9 is observed over a small length scale. At larger length scales the defects in the structure exhibit a fat-fractal distribution with exponent \ensuremath{\beta}\ensuremath{\approxeq}3.3.