X-Ray Analysis of the Structure of Premelted Layers at Ice Interfaces

X-ray diffraction patterns of a premelted layer of ice and liquid water were obtained by a glancing-incidence method. Diffuse intensity patterns due to the premelted layer exhibited variation with temperature. Fourier transformation of the intensity curves gave pair-correlation functions, where the first, second and third peaks were observed in the premelted layer and liquid water. This suggests that there is a short range order in their molecular distribution. The average intermolecular distances between the nearest neighbors were 1–2% smaller in the premelted layer than in liquid water.