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Updated: Apr 4, 2026

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
Hydrogen bonding in the ethanol-water dimer.
Ian A Finneran1, P Brandon Carroll, Marco A Allodi
1Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA. gab@gps.caltech.edu.
We determined the ground-state structure of the ethanol-water dimer using microwave spectroscopy. The dimer forms a water-donor/ethanol-acceptor complex with ethanol in a gauche conformation, stabilized by hydrogen bonds.
Area of Science:
- Physical Chemistry
- Molecular Spectroscopy
- Intermolecular Forces
Background:
- Understanding molecular clusters is crucial for chemical processes.
- The ethanol-water dimer structure influences hydrogen bonding networks.
Purpose of the Study:
- To determine the precise ground-state structure of the isolated ethanol-water dimer.
- To investigate the role of hydrogen bonding in stabilizing the dimer.
Main Methods:
- Chirped-pulse Fourier transform microwave spectroscopy (8-18 GHz).
- Isotopic substitutions and ab initio calculations for structural confirmation.
Main Results:
- First rotational spectrum of the ethanol-water dimer ground state obtained.
- Identified a water-donor/ethanol-acceptor conformer with ethanol in a gauche conformation.
- Observed stabilization through cooperation of strong (O-HO) and weak (C-HO) hydrogen bonds.
Conclusions:
- The determined structure is the ground-state conformer, consistent with prior vibrational spectroscopy studies.
- Rotational spectroscopy provides specific structural insights into the ethanol-water dimer.
- Cooperative hydrogen bonding plays a key role in dimer stability.
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