  The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful
experimental tool enabling accurate investigations of the dynamic phenomena in
molecular liquids. We introduced innovative experimental and fitting
procedures, that permit a safe deconvolution of sample response function from
the instrumental function. This is a critical issue in order to measure the
dynamics of sample presenting weak signal, e.g. liquid water. We report OKE
data on water measuring intermolecular vibrations and the structural relaxation
processes in an extended temperature range, inclusive of the supercooled
states. The unpreceded data quality makes possible a solid comparison with few
theoretical models; the multi-mode Brownian oscillator model, the Kubo's
discrete random jump model and the schematic mode-coupling model. All these
models produce reasonable good fits of the OKE data of stable liquid water,
i.e. over the freezing point. The features of water dynamics in the OKE data
becomes unambiguous only at lower temperatures, i.e. for water in the
metastable supercooled phase. Hence this data enable a valid comparison between
the model fits. We found that the schematic mode-coupling model provides the
more rigorous and complete model for water dynamics, even if is intrinsic
hydrodynamic approach hide the molecular information.
