サイエンス記事
広いエネルギー範囲で観測される水の構造とダイナミクス
キーワード:
confined water,
high pressure,
neutron diffraction,
quasi-elastic scattering,
inelastic scattering
2019 年 29 巻 2 号 p. 86-90
詳細
2019 年 29 巻 2 号 p. 86-90
It is well known that water has anomalous properties compared with other liquids. The anomalies of water arise from the hydrogen bonding network structure. The investigation of the static structure and dynamics over a wide time range by neutron scattering would be useful for elucidation of the origin of the anomalies. In the manuscript, our neutron scattering results for water and aqueous solution are reviewed. (1) Water structure and dynamics confined in mesoporous silica glass. The structure of confined water becomes enhanced without freezing with decreasing temperature. A fragile-strong crossover in the structural relaxation of water is observed at ~220 K. Dynamics of confined water is affected by the properties of the pore wall. (2) Dynamics of water and glycine confined in mesoporous silica glass. Glycine molecules exist near the pore wall at pH=5, whereas they prefer to hydration apart from the pore wall at pH=2. (3) Neutron Brillouin scattering of water. The ratio of the high-frequency sound velocity to the adiabatic one of water is ~2, reflecting the tetrahedral-like water structure. (4) Water structure under high pressure. From the O-O correlation function, it is found that the tetrahedral structure changes to the closed packed one like as simple liquids on compression, indicating that the hydrogen bonds between water molecules are largely bent at 1 GPa.
