Ordered breath figures on a volatile liquid surface of pure dichloromethane.

When water vapor comes into contact with a cold surface, it condenses into water droplets. This natural phenomenon is called breath figures (BFs). Interestingly, ordered BFs can be formed on a volatile liquid surface. Different volatile liquids can induce different BFs, but the growth process of ordered BFs is not fully understood. Although it is believed that BFs can form on the surface of a volatile liquid, such as dichloromethane, there is little experimental evidence to support this claim. Herein, the growth of BFs on a surface of pure dichloromethane without any polymer was observed in situ by an optical microscope (OM) in a static humid environment. The OM images were analyzed to obtain details, and the ordered breath figure arrays (BFAs) were observed on the volatile liquid surface. It is found that there are three distinct power-law growth exponents, and the growth of BFs followed a single droplet growth before coalescing. Moreover, it was observed that water droplets were rapidly moving throughout the water droplet growth. The growth dynamics of BFs on the volatile surface of pure dichloromethane have unique characteristics, which are different from the reported results on nonvolatile surfaces, volatile solutions with polymer, and pure carbon disulfide. These results provide direct evidence for ordered BFs from pure dichloromethane and help explain the mechanism of ordered BFs on volatile liquid surfaces. [ABSTRACT FROM AUTHOR]