Determination of the Equilibrium Constant and Resolution of the HOD Spectrum by Alternating Least-Squares and Infrared Analysis

The equilibrium between H 2 O, D 2 O, and HOD in the liquid phase has been analyzed for different concentrations of the reactants by using the attenuated total internal reflectance (ATR) technique. The infrared spectroscopic profiles of the equilibrium mixtures were broken down into the contributing components by the alternating least-squares (ALS) curve resolution technique. Furthermore, the concentration profiles of H 2 O, D 2 O, and HOD were determined together with the equilibrium constant. Band assignment of the resolved HOD spectrum was further carried out. The equilibrium constant determined in this work agrees excellently with values determined by both theoretical calculations and experiments.