Transient absorption of vibrationally excited water
We study the spectral response of the transition between the first and the second excited state of the OH stretch vibration of HDO dissolved in liquid D2O with two-color femtosecond mid-infrared spectroscopy. The spectral response of this transition differs strongly from the fundamental absorption spectrum of the OH stretch vibration. In addition, excitation of the OH stretch vibration is observed to lead to a change of the hydrogen-bond dynamics of liquid water. We show that both these observations can be described with a refined quantum-mechanical version of the LippincottSchroeder model for hydrogen-bonded OH.O systems.