Raman spectra and structure of water from -10 to 90.deg.
01 Jun 1974-The Journal of Physical Chemistry (American Chemical Society)-Vol. 78, Iss: 13, pp 1304-1313
About: This article is published in The Journal of Physical Chemistry.The article was published on 1974-06-01. It has received 325 citations till now. The article focuses on the topics: Raman spectroscopy & Raman scattering.
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TL;DR: A systematic procedure based on two-dimensional potentials of mean force for defining cutoffs for a given pair of distance and angular coordinates is developed and an electronic structure-based definition of hydrogen bonding in liquid water is developed, related to the electronic occupancy of the antibonding OH orbitals.
Abstract: X-ray and neutron diffractions, vibrational spectroscopy, and x-ray Raman scattering and absorption experiments on water are often interpreted in terms of hydrogen bonding. To this end a number of geometric definitions of hydrogen bonding in water have been developed. While all definitions of hydrogen bonding are to some extent arbitrary, those involving one distance and one angle for a given water dimer are unnecessarily so. In this paper the authors develop a systematic procedure based on two-dimensional potentials of mean force for defining cutoffs for a given pair of distance and angular coordinates. They also develop an electronic structure-based definition of hydrogen bonding in liquid water, related to the electronic occupancy of the antibonding OH orbitals. This definition turns out to be reasonably compatible with one of the distance-angle geometric definitions. These two definitions lead to an estimate of the number of hydrogen bonds per molecule in liquid simple point charge/extended (SPC/E) water of between 3.2 and 3.4. They also used these and other hydrogen-bond definitions to examine the dynamics of local hydrogen-bond number fluctuations, finding an approximate long-time decay constant for SPC/E water of between 0.8 and 0.9 ps, which corresponds to the time scale for local structural relaxation.
586 citations
TL;DR: In this article, Raman intensity data were obtained from liquid water between 3.5 and 89.3°C using holographic grating double and triple monochromators.
Abstract: Low frequency Δν=0–350 cm−1, Raman intensity data were obtained from liquid water between 3.5 and 89.3 °C using holographic grating double and triple monochromators. The spectra were Bose–Einstein (BE) corrected, I/(1+n), and the total integrated (absolute) contour intensities were treated by an elaboration of the Young–Westerdahl (YW) thermodynamic method, assuming conservation of hydrogen‐bonded (HB) and nonhydrogen‐bonded (NHB=bent and/or stretched, O–H O) nearest‐neighbor O–O pairs. A ΔH°1 value of 2.6±0.1 kcal/mol O–H ⋅⋅⋅ O or 5.2±0.2 kcal/mol H2O (11 kJ/mol O–H ⋅⋅⋅ O, or 22 kJ/mol H2O) resulted for the HB→NHB process. This intermolecular value agrees quantitatively with Raman and infrared ΔH° values from the one‐ and two‐phonon OH‐stretching regions, and from molecular dynamics, depolarized light scattering, neutron scattering, and ultrasonic absorption, thus indicating a common process. A population involving partial covalency of, i.e., charge transfer into, the H ⋅⋅⋅ O units of linear and/or weak...
550 citations
TL;DR: In this paper, the van't Hoff relationship was used to determine the hydrogen bond enthalpy of the Raman spectra from water in a range of conditions from ambient to above the critical point.
Abstract: The Raman spectrum from water was obtained for a range of conditions from ambient to above the critical point, 256 bar and 400 °C. A fluorescence-free sapphire high-pressure Raman cell was employed with which the Raman spectra from water were examined between 30 and 4000 cm−1. Computer deconvolution of the Raman OH-stretching contours allowed the hydrogen bond strength to be determined from the integrated component intensity ratios by use of the van’t Hoff relationship. This procedure yielded a hydrogen bond enthalpy of 2.53±0.10 kcal/mol which is in excellent agreement with previously reported values.
524 citations
TL;DR: The results demonstrate that the peak in the parallel-polarized Raman spectrum at about 3250 wavenumbers is collective in nature, and shows that while the coupling between chromophores is relatively modest, it nevertheless produces delocalization of the vibrational eigenstates over up to 12 Chromophores, which has a profound effect on the spectroscopy.
Abstract: IR and Raman (parallel- and perpendicular-polarized) spectra in the OH stretch region for liquid water were measured some years ago, but their interpretation is still controversial. In part, this is because theoretical calculation of such spectra for a neat liquid presents a formidable challenge due to the coupling between vibrational chromophores and the effects of motional narrowing. Recently we proposed an electronic structure/molecular dynamics method for calculating spectra of dilute HOD in liquid D(2)O, which relied on ab initio calculations on clusters to provide a map from nuclear coordinates of the molecules in the liquid to OH stretch frequencies, transition dipoles, and polarizabilities. Here we extend this approach to the calculation of couplings between chromophores. From the trajectories of the fluctuating local-mode frequencies, transition moments, and couplings, we use our recently developed time-averaging approximation to calculate the line shapes. Our results are in good agreement with experiment for the IR and Raman line shapes, and capture the significant differences among them. Our analysis shows that while the coupling between chromophores is relatively modest, it nevertheless produces delocalization of the vibrational eigenstates over up to 12 chromophores, which has a profound effect on the spectroscopy. In particular, our results demonstrate that the peak in the parallel-polarized Raman spectrum at about 3250 wavenumbers is collective in nature.
476 citations
TL;DR: In this article, a modification of the central-force model for liquid water is proposed; a spectroscopic potential is adapted to describe the intramolecular interactions, and liquid shifts of internal vibrational frequencies obtained from MD simulations are in good agreement with available spectroscopy data.
442 citations