Noncritical behavior of density fluctuations in supercooled water

We have measured the absolute structure factor of liquid water over the wave-number range 0.05<k<0.30 A${\mathrm{̊}}^{\mathrm{-}1}$ and temperature range -34<T<25 °C with small-angle x-ray scattering. The correlation lengths of density fluctuations are small and change very little with temperature, suggesting that supercooled water may not be approaching a proposed spinodal point. The increasing density fluctuations with supercooling in water appear to be due to an increasing fraction of water molecules participating in clusters, not an increasing range of correlations.