Spectral evidence of connected structures in liquid water: Effective Raman density of vibrational states

We present experimental results of the effective Raman density of states showing that water both in normal and supercooled states has a fracton behavior. We have unambiguously determined a crossover frequency ωco between the phonon and fracton regimes. The obtained spectral results and the temperature behavior of ωco are consistent with the correlated-site percolation model indicating the existence of four-bonded patches whose spatial extent increases with decreasing temperature. This picture for the water system is confirmed from the spectral results of two different water-alcohol mixtures; the first one with ethanol, which acts as a ``patch-breaking'' impurity, and the second one with butoxyethanol, which can be considered as a ``patch-increasing'' impurity.