Hydrogen bond in liquid water as a Brownian oscillator
Phys. Rev. Lett. , Volume 83 p. 2077- 2080
We present the first experimental observation of a vibrational dynamic Stokes shift. This dynamic Stokes shift is observed in a femtosecond pump-probe study on the OH-stretch vibration of HDO dissolved in D2O. We find that the Stokes shift has a value of approximately 70 cm – 1 and occurs with a time constant of approximately 500 femtoseconds. The measurements can be accurately described by modeling the hydrogen bond in liquid water as a Brownian oscillator.