On the role of hydrogen-bond exchanges in the spectral diffusion of water

The dynamics of a vibrational frequency in a condensed phase environment, i.e., the spectral diffusion, has attracted considerable interest over the last two decades. A significant impetus has been the development of two-dimensional infrared (2D-IR) photon-echo spectroscopy that represents a direct...

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Bibliographic Details
Published in:The Journal of chemical physics 2021-02, Vol.154 (6), p.064501-064501
Main Authors: Piskulich, Zeke A., Laage, Damien, Thompson, Ward H.
Format: Article
Language:English
Subjects:
Activation energy
Chemical Sciences
Diffusion
Dynamics
Exchanging
Fluctuation theory
Hydrogen
Hydrogen bonds
Infrared spectroscopy
or physical chemistry
Physics
Spectra
Theoretical and
Time
Time correlation functions
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Summary:The dynamics of a vibrational frequency in a condensed phase environment, i.e., the spectral diffusion, has attracted considerable interest over the last two decades. A significant impetus has been the development of two-dimensional infrared (2D-IR) photon-echo spectroscopy that represents a direct experimental probe of spectral diffusion, as measured by the frequency–frequency time correlation function (FFCF). In isotopically dilute water, which is perhaps the most thoroughly studied system, the standard interpretation of the longest timescale observed in the FFCF is that it is associated with hydrogen-bond exchange dynamics. Here, we investigate this connection by detailed analysis of both the spectral diffusion timescales and their associated activation energies. The latter are obtained from the recently developed fluctuation theory for the dynamics approach. The results show that the longest timescale of spectral diffusion obtained by the typical analysis used cannot be directly associated with hydrogen-bond exchanges. The hydrogen-bond exchange time does appear in the decay of the water FFCF, but only as an additional, small-amplitude (
ISSN:0021-9606
1089-7690
DOI:10.1063/5.0041270