KAGAKU KOGAKU RONBUNSHU, Vol.26, No.1, 40-44, 2000
Analysis of the liquid structure of water using the O-17-NMR chemical shift method
The changes in the liquid structure and the state of hydrogen bonds of water with respect to temperature change were examined experimentally using the O-17-chemical shift method. Three types of water of identical origin having different concentrations of dissolved salts were used as samples. The following results were obtained: 1) The O-17-chemical shift method is useful for analyzing the liquid structure of the water because O-17-chemical shift is not effected bq the concentration of dissolved salt and thus a continuous spectrum can he obtained. 2) Using a logarithmic temperature scale, the transition temperatures of the liquid structure of water are confirmed to he at 288 K and 313 K, which is consistent with values indicated by temperature dependency of density and specific heat of the water. 3) The temperature dependency of O-17-chemical shift can be explained using continuum and mixture models. 4) The correlation between O-17-chemical shift and half-width can be evaluated by displaying their temperature dependency along with the ratio of [H+] at 313 K and that at a given temperature.