Isotope effects in liquid water by infrared spectroscopy

Abstract

The light and heavy liquid water (H2O–D2O) mixtures in the 0–1 molar fraction were studied in the mid-infrared by Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Five principal factors were retrieved by factor analysis (FA). When D2O is mixed with H2O, the HDO formed because of the hopping nature of the proton (H or D) results in three types of molecules in equilibrium. Because of the nearest-neighbor interactions, the three molecules give rise to nine species. Some of the species evolve concomitantly with other species giving the five principal factors observed. We present the spectra of these factors with their abundances. The calculated probability of the species present at different molar fractions which when the concomitant species are combined gives the observed abundances. To appreciate clearly the difference between the principal spectra, a Gaussian simulation of the bands was made. Because of the numerous components that make up the stretch bands, they are not very sensitive to changes in composition of the solutions; nevertheless, they do indicate the presence of new entities other than the pure species. The deformation bands, more sensitive to such changes than the stretch bands, clearly indicate the presence of the three types of molecules as well as of intermediate species. These bands are sensitive to the two hydrogen bonds on the oxygen atom that a reference molecule makes with its nearest-neighbors, but not to the hydrogen bonds that the nearest-neighbors make with the next nearest neighbors.

Two-dimensional infrared spectroscopy of isotope-diluted ice Ih

“…1(b)] appears blueshifted for the ice phase in comparison to the liquid. 58 A selection of 2D IR spectra of the OH stretch vibration of HOD/D 2 O at T = 80K is shown in Fig. 2, upper row, for population times t 2 varied between 100 fs and 1 ps.…”

D/H fractionation in the H2–H2O system at supercritical water conditions: Compositional and hydrogen bonding effects

“…This correction was essential to properly characterize the OD stretching bands in D 2 O and HDO components because these bands occur within this frequency region (Walrafen et al, 1996;Max and Chapados, 2002;Cappa et al, 2007). This adjustment was accomplished by subtracting the background spectrum measured from the upper diamond outside the gasket area at the corresponding temperature and pressure.…”

Probing water dynamics with OH−

“…The OH stretching region of the vibrational spectrum of pure water and aqueous solutions has been extensively studied by both Raman and infrared spectroscopy [1][2][3][4][5], in a variety of thermodynamic conditions, ranging from the supercooled [6] to the supercritical [7] states, at very high pressures [8][9][10][11] or more recently in confined geometry [12]. Several studies have also been performed on electrolyte solutions [13][14][15][16], but the hydroxide solutions have received less attention than others and are only rarely quoted in the literature [17][18][19].…”