Evaporation Length Scales of Confined Water and Some Common Organic Liquids

When two macroscopic and repulsive surfaces are immersed in water, evaporation of the confined liquid is favored thermodynamically below a critical separation: the evaporation length scale. We use thermophysical property data to evaluate the evaporation length scale of water, and compare it to that of several common organic liquids over a broad range of temperatures, at atmospheric pressure. We show that water's evaporation length scale is of the order of 1 mu m, appreciably larger than generally thought. The evaporation length scale of several common organic liquids, although systematically smaller than water's, is likewise macroscopic, attesting to the generality of the phenomenon. The only physical property that causes water's evaporation length scale to be larger than that of other liquids is its surface tension. In the limit of small immersed surfaces, the evaporation length is proportional to the size of the immersed object, and does not depend on the confined liquid.