We have used femtosecond two-color midinfrared spectroscopy to determi
ne the temperature dependence of the OH-stretching lifetime in dilute
HDO:D2O solution, both in the liquid and solid (ice Ih) state. Like ma
ny other properties of water, the vibrational lifetime shows a remarka
ble temperature dependence: In liquid water the vibrational relaxation
of the OH-stretching mode is twice as slow as in ice, and becomes eve
n slower with increasing temperature.