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A hydrogen-bonding structure in self-formed nanodroplets of water adsorbed on amorphous silica revealed via surface-selective vibrational spectroscopy
Water adsorption onto a material surface is known to change macroscopic surface properties such as wettability and friction coefficient. While the role of the adsorbed water has been discussed for a long time, the interfacial structure of the adsorbed water has not been fully recognized in many case...
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Published in: | Physical chemistry chemical physics : PCCP 2020-01, Vol.22 (46), p.27031-27036 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Water adsorption onto a material surface is known to change macroscopic surface properties such as wettability and friction coefficient. While the role of the adsorbed water has been discussed for a long time, the interfacial structure of the adsorbed water has not been fully recognized in many cases. In this study, the hydration structure of water adsorbed on a vapor/silica interface at room temperature was studied
via
heterodyne-detected vibrational sum-frequency generation spectroscopy. The vibrational spectra of the interfacial molecules obtained here were different from those estimated
via
conventional sum-frequency generation spectroscopy. Interestingly, our results suggest that, at low humidity, the adsorbed water on silica forms nanodroplets instead of a uniform film. Because no silanol group was found to be hydrogen-bonding free, it was concluded that water molecules gather around the silanol group to form strongly hydrogen-bonded droplets. At high humidity, while the adsorbed water partially behaves like a bulk liquid, deprotonation of the silanol was not observed, unlike the case of silica surfaces in contact with bulk liquid water. |
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ISSN: | 1463-9076 1463-9084 |
DOI: | 10.1039/d0cp03207g |