Electric field fluctuations drive vibrational dephasing in water
J. Chem Phys. A , 109 (2005), p. 9424-9436
We present a microscopic description of the vibrational spectroscopy of the OH stretch of HOD in liquid D2O. Our model predicts that OH frequency correlations decay with a sharp and rapid (~35 femtoseconds) decrease, followed by a beat at ~125 femtoseconds from intermolecular oxygen vibrations. On a short time scale, (~200 femtoseconds) ultrafast infrared spectroscopy of the OH stretch is sensitive to localized intermolecular motions. For times longer than ~200 femtoseconds, cooperative molecular rearrangements drive dephasing. The interplay of electric field fluctuations, both local and cooperative, dictate vibrational frequency shifts and destroy vibrational coherence in water.
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