Orthogonalyzed H2O and D2O species obtained from infrared spectra of liquid water at several temperatures

Abstract

Infrared spectra of light and heavy liquid waters were obtained between room temperature and 100 °C. Stretch regions show large structureless bands whose intensities decrease with temperature with slight blue shifts. Isosbestic points indicate two types whose abundances vary with temperature: cold and hot waters. Second derivatives and band simulations were used in synergy to untangle spectral band components. For cold light and hot waters, six Gaussian components make up almost 98% of the 3-μm absorption. In these, the two principal components are ν3 and ν1. The last 2% are made of five weaker components. Likewise, the cold and hot heavy water 4-μm spectra are made of six principal (∼95%) and seven secondary components. Between ν3 and ν1 lie 2ν2 components: strong in heavy water and weak in light water. For both waters, hot species are slightly blue shifted with, however, a 40% intensity decrease. Comparison of the light water cold-hot difference spectrum with that of normalized heavy water indicates a major difference arising from the prominent presence of 2ν2 components in heavy water spectra.