Light Makes Water Evaporate
There is a new update to the world!
It appears water evaporates more when exposed to light. It’s been just discovered in a new study.
This paper was first shared on arXiv in October 2023 (link). Recently (on March 2024) a peer reviewed version has been released (link). After LK-99 (room temperature superconductor (link)) fiasco I learned to not get my hopes up just based on publications, but I think this study looks promising!
The key to this phenomenon lies in the interaction of light with the water molecules at the surface. When water is exposed to visible light, the energy from the light excites the water molecules, increasing their kinetic energy. This excitation makes it easier for water molecules to escape into the air as vapor. This process is referred to as the "Photomolecular Effect."
Understanding the Photomolecular Effect
At a molecular level, water has a network of hydrogen bonds that hold its molecules together in a quasi-structured, yet fluid arrangement. These hydrogen bonds are relatively weak compared to covalent bonds but are crucial for the unique properties of water. When visible light hits the water surface, photons impart energy to the water molecules. This energy increases the kinetic energy of the molecules, effectively "loosening" the structure and allowing more molecules to transition into the vapor phase.
What’s fascinating is that this process doesn’t just rely on the energy from the light. Once the water molecules are excited by the light, the surrounding air molecules can more easily carry away the water molecules. This means that the air itself, through its natural kinetic energy, assists in the evaporation process. As a result, the air cools down slightly as it expends energy in helping water molecules escape into the vapor phase.
Implications and Applications
The implications of this discovery are substantial. One potential application is in water purification systems. By utilizing the Photomolecular Effect, we could design systems that require less energy to evaporate and purify water, relying partially on ambient light and air. This could be particularly useful in areas with abundant sunlight but limited access to clean water.
Moreover, the cooling effect on the air could have environmental benefits. As the air cools down during the evaporation process, it could help mitigate some effects of climate change by reducing local temperatures. While this cooling effect is relatively small, in aggregate, it could contribute to more efficient climate control solutions.
Conclusion
I believe these are all good news! This leaves us with another method can be utilized for water evaporation therefore purification. Meanwhile doing that it cools the air down which we suffer from due to climate change!