Abstract
Evaporation is the process by which water changes from a liquid to a gas or vapor, and is a key step in Earth’s water cycle. At the molecular level, evaporation requires breaking at least one very strong intermolecular bond between two water molecules at the interface. Despite the importance of this process the molecular mechanism by which an evaporating water molecule gains sufficient energy to escape from the surface has remained elusive. Here, we show, using molecular dynamics simulations at the water-air interface with polarizable classical force field models, that the high kinetic energy of the evaporated water molecule is enabled by a well-timed making and breaking of hydrogen bonds involving at least three water molecules at the interface, the recoil of which allows one of the molecules to escape. The evaporation of water is thus enabled by concerted, ultrafast hydrogen-bond dynamics of interfacial water, and follows one specific molecular pathway.
- Received 22 June 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.236102
© 2015 American Physical Society
Focus
Water Molecules Need Help to Evaporate
Published 30 November 2015
Each time a liquid water molecule enters the vapor phase, a coordinated dance of several molecules is involved, according to simulations.
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