Researchers from MIT, led by mechanical engineer Gang Chen, have reported a potentially groundbreaking discovery suggesting that visible light, particularly in the green spectrum, might accelerate water evaporation beyond what is explained by heat alone. Traditionally, heat has been the primary driver of water evaporation, increasing molecular motion in liquid water. However, the new study indicates that photons of visible light may directly break the bonds between water molecules, releasing clusters of molecules into the air.
In experiments using porous hydrogels that absorb water, the researchers observed an evaporation rate higher than expected based on heat alone when exposed to visible light. The effect was more pronounced with green light, indicating a wavelength-dependent response. This finding opens up new possibilities for understanding the role of light in evaporation and its potential applications.
While the proposed mechanism needs further validation, scientists find the wavelength dependence and the absence of excess evaporation with heat alone as compelling evidence. If confirmed, this discovery could have practical implications, such as improving methods for freshwater production from saltwater.
Despite some unanswered questions and the need for additional research, the researchers believe that this effect might be prevalent in natural settings, occurring daily in water within porous materials like soil or plants and even in ocean foams.