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arXiv:2201.10385physics.chem-ph

Photomolecular Effect Leading to Water Evaporation Exceeding Thermal Limit

Yaodong Tu, Jiawei Zhou, Shaoting Lin, Mohammed AlShrah, Xuanhe Zhao, Gang Chen

Abstract

We report the discovery of photomolecular effect: cleavage of water clusters off surfaces by photons. This effect is demonstrated through surprising absorption of partially wetted hydrogel in the visible spectrum where both water and hydrogel materials' absorption are negligible. 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. Measurements of temperature and transmission spectrum of vapor above evaporating surfaces show clear signatures of water clusters. The photomolecular effect happens at liquid-vapor interface due to large electrical field gradients and quadrupole force on molecular clusters. This photomolecular evaporation process might be happening widely in nature, potentially impacting climate and plants growth, and can be exploited for clean water and drying technologies.

arXiv comments
45 pages, 18 figures
Journal reference
DOI
Subjects
physics.chem-phChemical Physics cond-mat.mes-hallMesoscale and Nanoscale Physics cond-mat.mtrl-sciMaterials Science cond-mat.softSoft Condensed Matter

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Linked by 3 identifiable commenters in 3 comments across 2 threads, from Nov 2023 to Nov 2023.

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Discussed in comments2 threads

  1. Light can make water evaporate without heat 1 comment

    • Worth noting that I’m going off the preprint since I don’t have PNAS access. https://arxiv.org/pdf/2201.10385.pdf

      elil17View on HNParent context

  2. Photomolecular effect leading to water evaporation exceeding the thermal limit 2 comments

    • I found https://arxiv.org/pdf/2201.10385.pdf by the same authors. If I read it correctly, it says the theoretical limit for thermal evaporation is 1.45 kg/(m²h), while experimentally, values as high as 4-5 kg/(m²h) and over 10 kg/(m²h) have been reported in two-, respectively…

      SomeoneView on HNParent context

    • An earlier discovery draft paper is freely available, but only guesses at mechanisms: https://arxiv.org/pdf/2201.10385.pdf This is one of those things that seems fairly obvious once pointed out: that the energy in light might be sufficient to directly break hydrogen bonds and…

      svntView on HNParent context

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