Mid-infrared fiber-optic attenuated total reflection spectroscopy of the solid-liquid phase transition of water

Measurements of mid-infrared (MIR) absorption spectra of water and heavy water were carried out by fiber-optic evanescent wave spectroscopy, using silver halide (AgClBr) infrared fibers. Such measurements were performed for the first time on one sample, during the solid-liquid phase transition. From the variation of the spectra with temperature we found a new isosbestic point (at 3280 cm^-1 for H₂O or at 2475 cm^-1 for D ₂O) and we identified five components of the O-H (O-D) stretch band. These phenomena have provided new information about the molecular structure of water.