Femtosecond mid-infrared pump-probe spectroscopy of water and ice
We have used femtosecond mid-infrared pump-probe spectroscopy on the OH-stretching mode of HDO dissolved in D2O to investigate both the orientational and vibrational dynamics of water and ice. The orientational data provide evidence for a two-component structure of liquid water. The vibrational lifetime of the OH-stretch mode shows a remarkable temperature dependence: in water it is twice as long as in ice, and is found to increase with temperature.