Possible mechanism of OH frequency shift dynamics in water

The results of the recent infrared pump-probe experiment are analyzed, in w hich the time evolution of the spectrum of the OH-stretching vibration exci ted by an ultrashort laser pulse in the dilute solution HDO/D2O was measure d, To interpret the results of the experiment, a formalism developed earlie r for a different application, optical transitions of the chromophoric mole cules in polar solvent, is used. A mechanism of the IR shift dynamics in wa ter is suggested, involving a-relaxation (structural relaxation), which may also be related to the dielectric behavior of water. A suggestion is made for computer simulations as well as for an experimental test of the propose d mechanism.