Near-Infrared Studies of the Structure of Water. I. Pure Water

The absorption bands of water in the 1.1-to-1.3-μ region have been measured. From the extinction coefficients, concentrations of water species involving 2,1, and 0 hydrogen bonds per molecule were calculated. The temperature dependence of these concentrations yielded a value of 3.7–4.5 kcal for the energy involved in breaking one mole of hydrogen bonds in water. On melting, 46% of the hydrogen bonds originally present in ice are broken; by 72°C the percentage broken has increased to 61. Further, the results were used in conjunction with the flickering cluster model of Frank and Wen to obtain an upper limit for the average size of the water polymers of 90 molecules of H2O at 20°C.