Vibrational relaxation and hydrogen-bond dynamics of HDO:H2O

Femtosecond two-color mid-infrared pump-probe spectroscopy is used to study the vibrational relaxation and the hydrogen-bond dynamics of HDO dissolved in liquid H₂O. By looking at the spectral dynamics of the OD stretch mode, direct information on the hydrogen-bond dynamics of the H₂O solvent is obtained. By fitting the data using the Brownian oscillator model, we determined the vibrational lifetime of the OD stretch vibration and the hydrogen-bond length correlation time. The hydrogen-bond correlation time of H₂O is significantly shorter than for D₂O, found previously.