Temperature dependence of vibrational relaxation in liquid H2O

We have determined the lifetime of the OH-stretch vibration in pure liquid water as a function of temperature using femtosecond mid-infrared pump-probe spectroscopy. The lifetime T-1 increases from 260+/-18 fs at T=298 K to 320+/-18 fs at T=358 K. The increase in lifetime with temperature can be quantitatively explained from the decrease in overlap resonance between the OH-stretch vibration and the overtone of the H-O-H bending mode. (C) 2002 American Institute of Physics.