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Updated: Jul 12, 2026

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
Ultrafast anisotropy dynamics of water molecules dissolved in acetonitrile
Dan Cringus1, Thomas L C Jansen, Maxim S Pshenichnikov
1Department of Physical Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Abstract:
Infrared pump-probe experiments are performed on isolated H(2)O molecules diluted in acetonitrile in the spectral region of the OH stretching vibration. The large separation between water molecules excludes intermolecular interactions, while acetonitrile as a solvent provides substantial hydrogen bonding. Intramolecular coupling between symmetric and asymmetric modes results in the anisotropy decay to the frequency-dependent values of approximately 0-0.2 with a 0.2 ps time constant. The experimental data are consistent with a theoretical model that includes intramolecular coupling, anharmonicity, and environmental fluctuations. Our results demonstrate that intramolecular processes are essential for the H(2)O stretching mode relaxation and therefore can compete with the intermolecular energy transfer in bulk water.
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