Evolution of foam structures in Langmuir monolayers of pentadecanoic acid

Abstract

Measurements are reported of the evolution of foam structures in monolayers of pentadecanoic acid at the air-water interface. The foams are observed by fluorescence microscopy. Various statistical properties of this random two-dimensional cellular structure have been determined: the second moment of the cell-side distribution is constant with time, the characteristic size grows according to a power law with an exponent \ensuremath{\approxeq}0.4, Aboav's law is obeyed, and the average cell perimeter is proportional to the number of sides. Comparisons are made with experiments on soap foams, metal grains, and simulations.