Analysis of hydrogen bonds is water using spectrum decomposition technique applied to near-infrared absorption spectra.

An absorption band assigned to the second overtone of an OH vibration of water was measured at varioustemperature (-120°C to 75°C). We employed spectrum decomposition technique to analyze fine structure of this absorption band. The absorption band was decomposed into five components which may be assigned to species with diffrent hydrogen bondings. The average number and energy of hydrogen bond were calculated from the fraction of each component and heat capacity at constant pressure. From this result the melting and vaporizing enthalpy of water were estimated to be a value of 7.8 and 44.6 kJ·mol-1, respectively. These values were in good agreement with the observed values, which indicating that the interpretation of the assignments of five component bands was ade-quate.