https://doi.org/10.1140/epjd/s10053-026-01186-z
Research - Atoms, Molecules, Ions, and Clusters
Solvent-dependent vibrational coupling and coherence decay of the nitro-substituent mode revealed by ultrafast spectroscopy
School of Physics and New Energy, Xuzhou University of Technology, No. 2, Lishui Road, 221018, Xuzhou, Jiangsu, China
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Received:
13
January
2026
Accepted:
10
May
2026
Published online:
1
June
2026
Abstract
In this experimental study, time-resolved coherent anti-Stokes Raman scattering (TR-CARS) spectroscopy, combined with frequency-resolved Fourier-transform (FT) analysis, is used to investigate vibrational coupling and coherence dynamics of the nitro-substituent mode in nitrobenzene and in binary mixtures with methanol and sulfolane. Nitrobenzene is chosen as a representative nitro-aromatic probe, while methanol and sulfolane serve as hydrogen-bonding and non-hydrogen-bonding solvent environments, respectively, enabling discrimination between solvent-specific intermolecular effects and more general solvent environment effects. Unlike previous studies that mainly focused on general vibrational energy transfer, phenyl-group effects, or substituent number effects, the present work examines whether the nitro-substituent mode at 1335 cm
acts as a mode-specific coupling center and whether its coherence decay is sensitive to the surrounding solvent environment. The results show that the 1335 cm nitro-substituent mode participates in intramolecular coupling with the nitrobenzene ring modes at 1108 and 1007 cm and in intermolecular coupling with the methanol C–H bending mode at 1470 cm and the sulfolane ring torsional mode at 1249 cm. Time-domain analysis further shows a clear solvent dependence of the coherence dephasing time of the nitro-substituent mode, which is 1099 ± 12.5 fs in neat nitrobenzene, 1006 ± 23 fs in the nitrobenzene–sulfolane mixture, and 650 ± 14 fs in the nitrobenzene–methanol mixture. The pronounced shortening in methanol is consistent with a methanol-specific intermolecular interaction, plausibly involving hydrogen bond donation to the nitro group, which may introduce an additional vibrational dephasing channel and accelerate coherence loss. These findings provide comparative spectroscopic evidence that the coherence dephasing of the nitro-substituent mode is highly sensitive to the local solvent environment and is likely influenced by hydrogen bond-mediated interactions.
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Zihang Ding and Kefan Cao have contributed equally to this work.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
