Plausible photomolecular effect leading to water evaporation exceeding the thermal limit
Name
tu-et-al-2023-plausible-photomolecular-effect-leading-to-water-evaporation-exceeding-the-thermal-limit.pdf
Description
Published version
Size
3.38 MB
Format
Adobe PDF
Checksum (MD5)
2df67796a8933879d3b171c7e3b833fe
Author(s)
Tu, Yaodong
Zhou, Jiawei
Lin, Shaoting
Alshrah, Mohammed
Zhao, Xuanhe
Chen, Gang
Date Issued
November 7, 2023
Journal
Proceedings of the National Academy of Sciences
Publisher
Proceedings of the National Academy of Sciences
Citation
Tu, Yaodong, Zhou, Jiawei, Lin, Shaoting, Alshrah, Mohammed, Zhao, Xuanhe et al. 2023. "Plausible photomolecular effect leading to water evaporation exceeding the thermal limit." Proceedings of the National Academy of Sciences, 120 (45).
Version
Final published version
Abstract
We report in this work several unexpected experimental observations on evaporation from hydrogels under visible light illumination. 1) Partially wetted hydrogels become absorbing in the visible spectral range, where the absorption by both the water and the hydrogel materials is negligible. 2) 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. 3) The evaporation rates are wavelength dependent, peaking at 520 nm. 4) Temperature of the vapor phase becomes cooler under light illumination and shows a flat region due to breaking-up of the clusters that saturates air. And 5) vapor phase transmission spectra under light show new features and peak shifts. We interpret these observations by introducing the hypothesis that photons in the visible spectrum can cleave water clusters off surfaces due to large electrical field gradients and quadrupole force on molecular clusters. We call the light-induced evaporation process the photomolecular effect. The photomolecular evaporation might be happening widely in nature, potentially impacting climate and plants’ growth, and can be exploited for clean water and energy technologies.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Creative Commons Attribution-Noncommercial-NoDerivatives
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DOI of Published Version
https://doi.org/10.1073/pnas.2312751120
