Water structure in 100 nm nanochannels revealed by nano X-ray diffractometry and Raman spectroscopy

Microscopic water structure confined in 100 nm nanofluidic channels was investigated with nano X-ray diffractometry and Raman spectroscopy. A new nano X-ray diffractometry device was fabricated to protect the dry-up of water in the nanochannels during a long-term (greater than 30 h) measurement. Bragg peaks from the substrate material, which affected the analysis of a radial distribution function (RDF), were completely removed by changing the materials. As a result, the small change of the RDF by the confinement effect of water was successfully revealed. Raman spectra suggested the strong hydrogen bonding of water in nanochannels. Based on both X-ray and Raman results, a stronger hydrogen-bonding network and higher density than bulk water were suggested for water in nanochannels. This information is significant to discuss the liquid property changes and the water structure in 10-100 nm spaces, which are seen in many chemical and biological systems. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the microscopic water structure confined in 100 nm nanofluidic channels using nano X-ray diffractometry and Raman spectroscopy. It revealed a small change in the radial distribution function (RDF) due to the confinement effect of water, suggesting stronger hydrogen-bonding network and higher density for water in nanochannels. This information is significant for understanding liquid property changes and water structure in 10-100 nm spaces found in various chemical and biological systems.