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MIT researchers discover "photomolecular effect": light alone can evaporate water without heat, a previously unknown physics phenomenon that could enable new technologies

How light can vaporize water without the need for heat

https://news.mit.edu/2024/how-light-can-vaporize-water-without-heat-0423

MIT researchers discovered that light can cause evaporation of water from a surface without the need for heat. This “photomolecular effect” could be important for understanding climate change and for improving some industrial processes.

How light can vaporize water without the need for heat

7 comments

Septimaeus

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Paper If I understand correctly, it relates to light’s behavior as both a particle and a wave. Photons can “shave” molecules off the surface of water, creating vapor.

The effect apparently peaks around 520 nm (the visible color cyan, which has lower thermal absorption) and at an angle of 45 deg. Would these results suggest it’s actually possible to induce evaporative cooling with the careful application of light?

Dubiousx99

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I wonder if it could be used to improve desalination techniques.

wyrmroot

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Was fully prepared for the answer to this to be that a couple extra molecules evaporating don’t make a big difference, but:

Under the optimum conditions of color, angle, and polarization, Lv says, “the evaporation rate is four times the thermal limit.”

That sounds legitimately exciting!

HubertManne

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am I the only one hoping for a simpler room temp humidifier?

threelonmusketeers

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Simpler and quieter perhaps, but not more efficient. Remember that the latent heat of vapourization has to come from somewhere.

Technology Connections has a great video on humidifiers: https://youtube.com/watch?v=oHeehYYgl28

HubertManne

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Yeah I was not thinking of more humiditification as much as quieter but still room temp and easier to clean and such.

webghost0101

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Steam exploit?