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New Atlas: Water can evaporate with just light, no heat, says surprising study (newatlas.com)

submitted 1 year ago by [email protected] to c/[email protected]

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[–] [email protected] 14 points 1 year ago (6 children)

So for the new study, scientists at MIT set out to investigate what might be happening. After a few basic experiments, they suspected that light itself was causing the excess evaporation. The idea is surprising because water doesn’t really absorb light – hence why you can see through it to a decent depth if it’s clean.

To really check their hypothesis, the scientists placed a hydrogel sample in a container on a scale, exposed it to different wavelengths of light in sequence, and measured the amount of mass it lost over time to evaporation. The equipment was carefully controlled and the lights shielded to prevent any heat being introduced to the system and messing with the results.

One possibility: The hydrogel is absorbing the light and emitting it as heat to the water thus increasing the evaporation.

[–] [email protected] 6 points 1 year ago

This article skips over a few points, heres the paper:

https://www.pnas.org/doi/10.1073/pnas.2312751120?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed

So your idea seems plausible at first, but more information leads to the proposed photo molecular effect:

Illumination of hydrogel under solar or visible-spectrum light-emitting diode leads to evaporation rates exceeding the thermal evaporation limit, even in hydrogels without additional absorbers.

Also the absorption of both the water and gel are negligible

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