Something you should also know, from the National Academy of Sciences:

"Temperature dependence of the two-dimensional infrared spectrum of liquid H2O

D. Kraemer*, M. L. Cowan*, A. Paarmann*, N. Huse, E. T. J. Nibbering, T. Elsaesser, and R. J. Dwayne Miller*,

*Institute for Optical Sciences, Departments of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, ON, Canada M5S3H6; and Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany

Edited by Robin M. Hochstrasser, University of Pennsylvania, Philadelphia, PA, and approved November 12, 2007 (received for review June 22, 2007)


Two-dimensional infrared photon-echo measurements of the OH stretching vibration in liquid H2O are performed at various temperatures. Spectral diffusion and resonant energy transfer occur on a time scale much shorter than the average hydrogen bond lifetime of 1 ps.

Room temperature measurements show a loss of frequency and, thus, structural correlations on a 50-fs time scale. Weakly hydrogen-bonded OH stretching oscillators absorbing at high frequencies undergo slower spectral diffusion than strongly bonded oscillators.

In the temperature range from 340 to 274 K, the loss in memory slows down with decreasing temperature. At 274 K, frequency correlations in the OH stretch vibration persist beyond 200 fs, pointing to a reduction in dephasing by librational excitations.

Polarization-resolved pump-probe studies give a resonant intermolecular energy transfer time of 80 fs, which is unaffected by temperature. At low temperature, structural correlations persist longer than the energy transfer time, suggesting a delocalization of OH stretching excitations over several water molecules. "