Polarization-selective pump-probe and echo experiments on the OH vibration of HOD in D2O with 45−femtosecond (fs) infrared pulses are analyzed self-consistently to reveal the time scales for vibrational relaxation, dephasing, and molecular reorientation. Librational motion and hydrogen bond fluctuations on 50- and 180−fs time scales precede picosecond collective reorganization.
Loparo, J. J., Fecko, C. J., Eaves, J. D., Roberts, S. T. and Tokmakoff, A. Reorientational and configurational fluctuations in water observed on molecular length scales. Phys. Rev. B. 70, 180204 (2004)