Percolation theory for supercooled water predicts an enhanced intensity in the low-q range of the spectrum. In small-angle x-ray measurements on water in the ‖q‖ range 0.4–1.8 ${\mathrm{nm}}^{\mathrm{-}1}$ and the temperature range 273–253 K, no enhanced intensity could be measured. The spectra just follow the normal equilibrium thermodynamic behavior. A nonequilibrium enhanced intensity is observed in the spectra of supercooled water in vertically mounted capillaries in the ‖q‖ range below 0.3 ${\mathrm{nm}}^{\mathrm{-}1}$. This intensity is due to convection in the capillaries.

• Received 24 September 1991

DOI:https://doi.org/10.1103/PhysRevA.45.5731