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2D Raman-THz Spectroscopy of Binary CHBr3-MeOH Solvent Mixture.
A Shalit1, S J Mousavi1, P Hamm1
1Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
The Journal of Physical Chemistry. B
|January 6, 2021
Summary
Hybrid 2D Raman-terahertz (THz) spectroscopy reveals new low-frequency modes in CHBr3-MeOH mixtures. Hydrogen bonding between solvents creates distinct spectral signatures, indicating coupled intermolecular vibrations.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Materials Science
Background:
- Understanding solvent-solvent interactions is crucial for predicting mixture properties.
- Terahertz (THz) spectroscopy probes collective intermolecular motions in liquids.
- Raman spectroscopy provides information on intramolecular vibrations.
Purpose of the Study:
- To investigate the coupling between intramolecular and intermolecular dynamics in binary solvent mixtures.
- To identify new low-frequency modes arising from hydrogen bonding in CHBr3-MeOH mixtures.
- To utilize hybrid 2D Raman-THz spectroscopy for probing solvent interactions.
Main Methods:
- Hybrid 2D Raman-terahertz (THz) spectroscopy was employed.
- Measurements were conducted on binary CHBr3-MeOH solvent mixtures across a 1-7 THz frequency range.
- 1D absorption measurements of neat methanol and CHBr3-CS2 mixtures were used for comparison.
Main Results:
- A new cross-peak signature appeared in the 2D spectrum of the CHBr3-MeOH mixture at a 0.3 molar fraction of MeOH.
- This new peak indicates coupling between the CHBr3 intramolecular bending mode and new low-frequency modes.
- These new modes are attributed to hydrogen bond interactions between CHBr3 and MeOH.
Conclusions:
- Hybrid 2D Raman-THz spectroscopy effectively detects changes in intermolecular dynamics due to hydrogen bonding.
- The study identifies novel low-frequency modes in binary solvent mixtures driven by specific solvent-solvent interactions.
- This technique offers a powerful tool for characterizing complex liquid mixtures.
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