Revealing excess protons in the infrared spectrum of liquid water

The most common species in liquid water, next to neutral H\(_2\)O molecules, are the H\(_3\)O\(^+\) and OH\(^-\) ions. In a dynamic picture, their exact concentrations depend on the time scale at which these are probed. Here, using a spectral-weight analysis, we experimentally resolve the fingerprin...

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Bibliographic Details
Published in:arXiv.org 2020-07
Main Authors: Artemov, V G, Uykur, E, Roh, S, Pronin, A V, Ouerdane, H, Dressel, M
Format: Article
Language:English
Subjects:
Femtochemistry
Infrared spectroscopy
Ionic liquids
Water
Water chemistry
Weight analysis
Online Access:Get full text
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Summary:The most common species in liquid water, next to neutral H\(_2\)O molecules, are the H\(_3\)O\(^+\) and OH\(^-\) ions. In a dynamic picture, their exact concentrations depend on the time scale at which these are probed. Here, using a spectral-weight analysis, we experimentally resolve the fingerprints of the elusive fluctuations-born short-living H\(_3\)O\(^+\), DH\(_2\)O\(^+\), HD\(_2\)O\(^+\), and D\(_3\)O\(^+\) ions in the IR spectra of light (H\(_2\)O), heavy (D\(_2\)O), and semi-heavy (HDO) water. We find that short-living ions, with concentrations reaching \(\sim 2\%\) of the content of water molecules, coexist with long-living pH-active ions on the picosecond timescale, thus making liquid water an effective ionic liquid in femtochemistry.
ISSN:2331-8422
DOI:10.48550/arxiv.1910.07578