Issue 17, 2022

UV resonance Raman spectroscopy of weakly hydrogen-bonded water in the liquid phase and on ice and snow surfaces

Abstract

The hydrogen bond network has a major role in determining the physical and chemical properties of water both in the solid and in the liquid state. In the bulk liquid phase, there is a coexistence of water molecules with different degrees of coordination and their relative amount changes according to the conditions (e.g., temperature, presence of solutes). Ice shows a larger amount of topologically under-coordinated water molecules at the surface as compared to the bulk. Snow is composed of many ice crystallites, and it differs from bulk ice because of the much larger specific surface area. The OH-stretching band is the most intense signal of the Raman spectrum of water, and it gives direct insight about the hydrogen bond network. In this work we compared the OH-stretching region of the Raman spectra of water, ice and snow acquired with excitations in the visible (532 nm) and in the UV-C range (250–200 nm) by exploiting the tunability of the synchrotron radiation. By moving towards the highest energy excitation we observed in liquid water a monotonic increase of the relative intensities of the peaks associated with weakly hydrogen-bonded water molecules. With visible excitation, the Raman spectrum of snow displays a larger contribution from weakly hydrogen-bonded water molecules at the surfaces when compared to the spectrum of bulk ice. By using excitation sources in the UV-C range, we observe a further enhancement of the contribution of the surfaces in the spectra of snow. By considering the reported changes of the water absorption coefficient in relation to the hydrogen bonding environment, we interpreted our results as a preferential pre-resonance excitation of weakly hydrogen-bonded water molecules induced by the UV-C sources.

Graphical abstract: UV resonance Raman spectroscopy of weakly hydrogen-bonded water in the liquid phase and on ice and snow surfaces

Article information

Article type
Paper
Submitted
04 3 2022
Accepted
13 4 2022
First published
14 4 2022
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2022,24, 10499-10505

UV resonance Raman spectroscopy of weakly hydrogen-bonded water in the liquid phase and on ice and snow surfaces

E. Maggiore, M. Tortora, B. Rossi, M. Tommasini and P. M. Ossi, Phys. Chem. Chem. Phys., 2022, 24, 10499 DOI: 10.1039/D2CP01072K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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