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Journal ArticleDOI

Derivative analysis of Raman spectra of liquid water in the OH (D) stretching region

01 May 1987-Journal of Molecular Structure (Elsevier)-Vol. 158, pp 195-204
Abstract: Second derivative analysis of Raman spectra of H2O, D2O and HOD in liquid phase at room temperature for parallel and perpendicular polarized modes in the OH and OD stretching regions is reported. Five components obtained at approximately 3215, 3375, 3455, 3535 and 3640 cm−1 for the second derivative plots of Raman spectra of liquid water are explained as due to the presence of three types of associated water species with (i) both OH bonds involved in moderately strong hydrogen bonds (SS), (ii) both OH bonds involved in weak hydrogen bonds (WW), and (iii) one OH bond involved in strong and one in weak hydrogen bonds (SW) respectively. The derivative plots obtained for Raman spectra of D2O and HOD also contain features expected to be present on the basis of this model. more

Topics: Raman spectroscopy (55%), Hydrogen bond (52%)
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Journal ArticleDOI
05 May 1993-Chemical Geology
Abstract: A high-temperature, high-pressure optical cell has been developed for the study of aqueous solutions by Raman spectroscopy. The disk-shaped cell has a sample volume of < 1 ml and utilizes diamond or sapphire windows set at 90° to one-another. Temperatures to 700°C and pressures to 4000 bar have been attained as measured using an internal thermocouple and a strain gauge. The apparatus was employed in the study of water to 500°C and 2000 bar with spectra of the OH stretching mode being collected at intervals of 50°C and 250 bar. A low-frequency shoulder between 3250 and 3300 cm−1 was found to persist to the maximum temperatures to at least 450°C at pressures above those of the liquid vapor curve; its intensity decreased with increasing temperature and decreasing pressure. The frequency of the maximum intensity of the spectral envelope increased dramatically with temperature to above 250°C and was found to be linear with respect to density and independent of temperature at constant density above 250°C. Similar behavior is seen for the viscosity, dielectric constant and the limiting equivalent conductances of pure water. The data indicate the presence of intermolecular hydrogen bonding to temperatures to well above 300°C at densities above the critical density. more

117 citations

Journal ArticleDOI
16 Dec 2015-Chemical Physics
Abstract: The effect of hydrogen carbonate (HCO 3 − ) and cations (Na + , K + ) solvated in water were revisited according to high spectrally resolved Raman measurements. Water solutions with different bicarbonate concentrations or added with increasing amounts of monovalent cations were examined with respect to their Raman spectra both in the bulk state and at the solid/liquid interface with a silicon nitride (Si 3 N 4 ) bioceramic. Spectroscopic calibrations confirmed that the Raman emission from OH-stretching in water is sensitive to molarity variations (in the order of tens of mM). The concentration gradient developed at the solid/liquid interface in cation-added solutions interacting with a Si 3 N 4 surface was measured and found to be peculiar to individual cations. Local variation in pH was detected in ionic solutions interacting with Si 3 N 4 samples, which might represent a useful property for Si 3 N 4 in a number of biomedical applications. more

17 citations

Journal ArticleDOI
Abstract: A general model of the liquid water structure consistent with its physical, chemical, structural, and also biological properties has not been described in the literature so far. Therefore, different structure models of liquid water have been taken into account in relation to its OH stretching Raman modes. Some factors (structure factor, H-bond cooperativity) typical of liquid and biological water have been considered. Also, the different roles played by water in biological systems are elucidated and discussed by means of a few general structure models, suitable for explaining the perturbations induced on liquid water by solutes (ionic, acids and bases, apolar) and surfaces. In particular, the possibility of strong acid—base H-bond interactions between different groups has been explored together with the biological role of water. Furthermore, the modulating effect of water on the H-bond strength and the consequent properties have been hypothesized. Finally, the behaviour of water structure in tissues and its possible correlation with normal and pathological conditions are reported. more

8 citations

Journal ArticleDOI
M. C. Shivaglal1, Surjit Singh1Institutions (1)
Abstract: On the basis of the two state model proposed by Luck it is suggested that the Raman spectrum for water can be explained on the basis of the presence of free and hydrogen bonded OH bonds. The stretching force constants in the associated species present in liquid water are found to be in general agreement with the observed bands due to free and hydrogen bonded OH stretching modes in the first overtone IR and the fundamental Raman spectra. more

2 citations

Book ChapterDOI
01 Jan 1993-
Abstract: The role of water in life processes is very important but very complex too depending on the structure of liquid water and on the particular physical and chemical properties of this hydride, and also on the interactions between water and biological molecules (hydration water, water interacting with acids and bases, perturbations induced on water by Van der Waals associations, surface-modified water, etc.). In this work the H-bond interactions of liquid water alone, adsorbed on surfaces and in biological systems will be particularly developed putting emphasis on the correlations between the strength of the interactions and the biological role. In some cases the results obtained by infrared and Raman vibrational spectroscopy will be referred. more

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01 Sep 1982-
Abstract: Infrared Spectroscopy of the Electrode-Electrolyte Solution Interface Infrared Spectral Studies of DNA Conformations Vibrational Analysis of the Retinal Isomers A Unified View of Raman, Resonance Raman and Fluorescence Spectroscopy (and their Analogues in Two-Photon Absorption) Magnetic Raman Optical Acitivity The Resonance Raman Effect and Depolarization in Vibrational Raman Scattering Low Frequency Depolarized Light Scattering from Liquids and Solutions. more

1,233 citations

Journal ArticleDOI
Abstract: Integrated Raman intensities of the spectral contour arising from the intermolecular librational motions of pure water have been obtained in the temperature range of ∼10°—95°C. In addition, integrated intensities of nearly symmetric librational components centered near ∼475 and ∼710 cm−1 were obtained from manual contour analysis according to two components. However, contour analysis was also accomplished by means of a special‐purpose analog computer, and three Gaussian librational components having average frequencies of 439, 538, and 717 cm−1 were thus revealed. The total contour intensity, the manually determined component intensities, and the Gaussian component intensities were found to have the same temperature dependence, and that dependence was found to be in excellent quantitative agreement with the previously reported temperature dependence of the hydrogen‐bond‐stretching intensity [J. Chem. Phys. 44, 1546 (1966)]. Integrated Raman intensities of pure water were also obtained in the temperature range of 10°—90°C for the intramolecular valence and deformation contours in the spectral region of ∼2800–3900 cm−1, and near 1645 cm−1, respectively. The integrated intensity of the deformation contour was found to be nearly independent of temperature, but the total integrated intensity of the intramolecular valence contour was found to decrease with increasing temperature. However, heights of the high‐frequency portion of the intramolecular valence contour were observed to increase, whereas heights of the low‐frequency portion were observed to decrease at nearly the same rate, with increasing temperature. An isosbestic point was also found at approximately 3460 cm−1. Further, computeranalysis revealed the existence of four Gaussian components having opposite temperature dependences in pairs—two intense valence components at ∼3247 and ∼3435 cm−1 were found to decrease in intensity with increasing temperature, and two weak components at ∼3535 and ∼3622 cm−1 were found to increase in intensity. Computeranalysis of infrared absorbance spectra also revealed four Gaussian components at approximately 3240, 3435, 3540, and 3620 cm−1. The quantitative agreements involving temperature dependences of the intermolecular hydrogen‐bond‐stretching and librational intensities, as well as the intramolecular valence data, would appear to preclude models of water structure involving consecutive hydrogen‐bond breakage. Continuum models of water structure are also precluded by the inter‐ and intramolecular intensity dependences, and particularly by the isosbestic point in the intramolecular valence region, but a model involving an equilibrium between two forms of water is consistent with all of the data. The two forms refer to water molecules which have or have not surmounted a barrier arising from a partially covalent hydrogen‐bond potential of C 2v symmetry, and they may be described as nonhydrogen‐bonded monomeric water, and as lattice water, respectively. Polarized argon‐ion‐laser—Raman spectra were also obtained in the intermolecular frequency region of the water spectrum, and the depolarization ratios of the intermolecular Raman bands were found to be in complete agreement with predictions from intermolecular C 2v symmetry. Studies of the intramolecular valence region were also made with polarized mercury excitation, and the spectra were analyzed by the analog method. Short‐lived CS intramolecular perturbations were indicated by the observed depolarization ratios of the four Gaussian valence components. Accordingly, CS intramolecular valence perturbations occur in the lattice water, as well as in the nonhydrogen‐bonded water, but the perturbations are of little importance on the intermolecular time scale. more

459 citations

Journal ArticleDOI
William F. Maddams1Institutions (1)
Abstract: There is an increasing awareness that the separation of over-lapping bands by the mathematical technique of curve fitting offers many pitfalls and should not be undertaken lightly. This review discusses critically the various factors involved, with particular reference to vibrational band systems; other types of overlapping band systems encountered in analytical work are considered in less detail. Five parameters are involved: the number of component bands, their positions, shapes and widths, and the form of the baseline. Curve fitting, by a least squares optimization method to a suitable goodness of fit criterion, is considerably facilitated if approximate values for some of the parameters are known at the outset. The methods available for peak finding are discussed and, although not free from problems, are reasonably effective. Similarly, band shapes can usually be defined semiquantitatively. However, it is seldom possible to obtain prior information on band widths; these should be determined during the curve fitting calculations. Although statistical goodness of fit criteria are available they should be used in conjunction with a visual plot, to locate any regions of poor fit. Furthermore, the overriding consideration must always be that the computer fit is plausible in terms of acceptable chemical species for the system being examined. more

340 citations