Structural changes in low temperature water

Previous experiments on the neutron structure factor S(q) for heavy water near 11.2°C have been extended so that the next term in the Taylor expansion may be examined. An improved result for the isochoric temperature derivative of S(q) at 11.2°C is obtained. These data and those for the (ΔT)² coefficient in the Taylor expansion may be explained on a simple basis: namely that OH and HH distances between neighbouring molecules vary as (T  t₀)⁻ⁿ where (T  T₀) ≈ 1200n for T ≈ 300 K.