Resolving the Nature of the Lowest-Frequency Raman Mode of Liquid Water.
- 1SISAA - Scuola Internazionale Superiore di Studi Avanzati , 34136Trieste, Italy.
- 2Center for Solvation Science ZEMOS, Ruhr-Universität Bochum, 44780Bochum, Germany.
- 3Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780Bochum, Germany.
Abstract
The lowest-frequency Raman mode of water, observed through depolarized light scattering or optical Kerr effect techniques, is routinely used to track dynamic changes of interfacial water near ions or biomolecules. Despite this broad importance, its microscopic origin and relation to dielectric relaxation remains debated since decades─with conflicting interpretations even for pure water. To resolve this controversy, we first accurately compute the Raman spectrum down to a few GHz based on ab initio simulations. Second, we introduce detailed decomposition analyses down to the dynamics of nuclei and electrons to reveal that the rotational and translational contributions are equally important. Third, strong negative orientational cross-correlations as well as internal field effects are found to modify the rotational component in very distinct ways. Overall, our analysis down to the electronic structure level provides an unexpectedly complex mechanistic scenario that fully resolves the long-standing debate concerning the lowest-frequency Raman mode of water and its relation to the dielectric spectrum.
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BibTeX
@article{pabst2026resolving,
title = {{Resolving the Nature of the Lowest-Frequency Raman Mode of Liquid Water.}},
author = {Florian Pabst and Harald Forbert and Dominik Marx},
journal = {The journal of physical chemistry letters},
year = {2026},
month = oct,
doi = {10.1021/acs.jpclett.6c02937},
url = {https://europepmc.org/article/MED/42918234},
note = {CC BY},
}
RIS
TY - JOUR
TI - Resolving the Nature of the Lowest-Frequency Raman Mode of Liquid Water.
AU - Florian Pabst
AU - Harald Forbert
AU - Dominik Marx
PY - 2026
DA - 2026/10/01
JO - The journal of physical chemistry letters
DO - 10.1021/acs.jpclett.6c02937
UR - https://europepmc.org/article/MED/42918234
AB - The lowest-frequency Raman mode of water, observed through depolarized light scattering or optical Kerr effect techniques, is routinely used to track dynamic changes of interfacial water near ions or biomolecules. Despite this broad importance, its microscopic origin and relation to dielectric relaxation remains debated since decades─with conflicting interpretations even for pure water. To resolve this controversy, we first accurately compute the Raman spectrum down to a few GHz based on ab initio simulations. Second, we introduce detailed decomposition analyses down to the dynamics of nuclei and electrons to reveal that the rotational and translational contributions are equally important. Third, strong negative orientational cross-correlations as well as internal field effects are found to modify the rotational component in very distinct ways. Overall, our analysis down to the electronic structure level provides an unexpectedly complex mechanistic scenario that fully resolves the long-standing debate concerning the lowest-frequency Raman mode of water and its relation to the dielectric spectrum.
SN - 1948-7185
ER -