Refractive index of nanoconfined water reveals its anomalous physical properties.

Autor:	Le THH; Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan and Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan. thu.le@riken.jp., Morita A; Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan and Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Nishikyo, Kyoto 615-8520, Japan., Tanaka T; Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan. thu.le@riken.jp and Metamaterials Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan and Institute of Post-LED Photonics, Tokushima University, Minami-Jyosanjima, Tokushima 770-8560, Japan.
Jazyk:	angličtina
Zdroj:	Nanoscale horizons [Nanoscale Horiz] 2020 Jun 02; Vol. 5 (6), pp. 1016-1024.
DOI:	10.1039/d0nh00180e
Abstrakt:	Despite extensive studies on the distinctive properties of water confined in a nanospace, the underlying mechanism and significance of the lengthscale involved in the confinement effects are still subjects of controversy. The dielectric constant and the refractive index in particular are key parameters in modeling and understanding nanoconfined water, yet experimental evidence is lacking. We report the measurement of the refractive indices of water in 10-100 nm spaces by exploiting the confinement of water and localized surface plasmons in a physicochemically well-defined nanocavity. The results revealed significantly low values and the scaling behavior of the out-of-plane refractive index n⊥ of confined water. They are attributed to the polarization suppression at the interfaces and the long-range correlation in electronic polarization facilitated by the strengthened H-bonding network. Using the refractive index as a sensing probe, we also observed anomalous stability of water structures over a wide range of temperature. Our measurement results provide essential feedback information for benchmarking water models and molecular interactions under nanoconfinement. This study also opens up a new methodology of using plasmon resonance in characterizing nanoconfined molecules and chemical reactions, and thus gives us fundamental insight into confinement effects.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu