Near infrared spectra and the disrupted network model of normal and supercooled water

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Abstract
The near IR (overtone) spectra of water, H2O–D2O solutions, and a glass‐forming glycerol +D2O solution have been measured in the temperature range 80 to −30 °C (−120 °C for the glycerol +D2O solution) using emulsion samples to gain access to the deep supercooling range. At −30 °C the intensity attributed to weakly hydrogen bonded –OH is greatly diminished and a small extrapolation in the latter case leads to a spectrum closely similar to that of the vitreous glycerol +D2O solution. This is a very broad spectrum, extending from 1.4–1.65 μm, which we associate with a fully bonded and immobile quasilattice in which there is a distribution of hydrogen bond strengths. The changes in intensity which occur with rise in temperature are seen to be consistent with an ‘‘exciting across the centroid’’ model (a weak bond⇄strong bond exchange) suggested by Stillinger and Rahman on the basis of MD calculations. The enthalpy change for this process is found to be 3.0 kcal/mol, consistent with light‐scattering data for the hydrogen bond‐breaking energy.