Study of the structure of a water molecular assembly in a hydrophobic nanospace at low temperature with in situ X-ray diffraction

The X-ray diffraction patterns of water molecules adsorbed in two kinds of slit-shaped graphitic micropores (micropore width: 0.75 and 1.13 nm) were measured from 143 to 303 K, and analyzed by an electron radial distribution function analysis. The formation of an ordered assembly structure of water molecules in the graphitic micropores at 303 K was evidenced. The structure of the water molecules in the 0.75 nm pore was more ordered compared with that of the 1.13 nm pore, although the water molecules became less mobile with lowering temperature. The water molecular assembly in the graphitic micropores had no clear phase transition point.