Raman Spectral Studies of Water Structure

Walrafen, G. E.

doi:10.1063/1.1724992

Cited by 579 publications

(370 citation statements)

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“…5 the simulated and experimental IR spectra [45][46][47][48][49] in different frequency ranges are reported, and the results appear to be satisfactory. In particular, the O-H stretching band, in the frequency range 3400-3700 cm Ϫ1 , is red-shifted with respect to the gas phase frequencies ͑3660 and 3754 cm Ϫ1 ͒ reported in Ref.…”

Section: A Liquid Watermentioning

confidence: 96%

Electric-field-dependent empirical potentials for molecules and crystals: A first application to flexible water molecule adsorbed in zeolites

Cicu

Demontis

Spanu

et al. 2000

The Journal of Chemical Physics

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A general method to include electric-field-dependent terms in empirical potential functions representing interatomic interactions is proposed. It is applied to derive an intramolecular potential model for the water molecule able to reproduce the effects of an electric field on its geometry and dynamics: to enlarge the HOH angle, to increase slightly the OH bond lengths, to red-shift the stretching vibrational frequencies, and to blue-shift slightly the bending mode frequency. These effects have been detected experimentally for water adsorbed in zeolites and have been confirmed by quantum mechanical calculations. The electric-field-dependent intramolecular potential model for water has been combined with a newly refined intermolecular potential for bulk water and with new potentials representing cation-water and aluminosilicate-water interactions in order to simulate, by classical molecular dynamics ͑MD͒ technique, the behavior of water adsorbed in zeolites. The performances of the model have been checked by a MD simulation of liquid water at room temperature, by the structural and vibrational properties of the water dimer, and by test MD calculations on a hydrated natural zeolite ͑natrolite͒. The results are encouraging, and the simulations will be extended to study the behavior of water adsorbed in other zeolites, including diffusion and some aspects of ion exchange processes.

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Section: A Liquid Watermentioning

confidence: 96%

Electric-field-dependent empirical potentials for molecules and crystals: A first application to flexible water molecule adsorbed in zeolites

Cicu

Demontis

Spanu

et al. 2000

The Journal of Chemical Physics

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“…Between 18 and 120 THz (600-4000 cm À1 ), pure water exhibits two noticeable dispersions assigned to the H-O-H bending (49 THz) and O-H stretching (~100 THz) (99). Especially, the latter is strongly coupled with intermolecular HB dynamics (49)(50)(51)(52)(55)(56)(57)(58), and in general, the O-H stretching frequency red-shifts as the intermolecular HB becomes stronger (100)(101)(102)(103)(104). On the other hand, the complex dielectric constant of albumin crystal exhibits the several amide bands (66,105,106) between 30 and 50 THz, the C-H stretching (87 THz) (107), and N-H stretching (~100 THz) (66) in the MIR region.…”

Section: Derivation Of O-h Stretching Of Hydration Watermentioning

confidence: 99%

“…In addition, an O-H stretching vibration around 100 THz (3330 cm À1 ) has been conventionally used as an index to estimate the HB strength (49)(50)(51)(52)(53)(54)(55)(56)(57)(58). In general, the stronger the HBs that a given water molecule establishes with its neighbors, the more red-shifted is the O-H stretching frequency (49,57,58).…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

Shiraga

Ogawa

Kondo

2016

Biophysical Journal

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The dynamical and structural properties of water at protein interfaces were characterized on the basis of the broadband complex dielectric constant (0.25 to 400 THz) of albumin aqueous solutions. Our analysis of the dielectric responses between 0.25 and 12 THz first revealed hydration water with retarded reorientational dynamics extending~8.5 Å (corresponding to three to four layers) out from the albumin surface. Second, the number of nonhydrogen-bonded water was decreased in the presence of the albumin solute, indicating protein inhibits the fragmentation of the water hydrogen-bond network. Finally, water molecules at the albumin interface were found to form a distorted hydrogen-bond structure due to topological and energetic disorder of the protein surface. In addition, the intramolecular O-H stretching vibration of water (~100 THz), which is sensitive to hydrogen-bond environment, pointed to a trend that hydration water has a larger population of strongly hydrogen-bonded water molecules compared with that of bulk water. From these experimental results, we concluded that the ''strengthened'' water hydrogen bonds at the protein interface dynamically slow down the reorientational motion of water and form the less-defective hydrogen-bond network by inhibiting the fragmentation of water-water hydrogen bonds. Nevertheless, such a strengthened water hydrogen-bond network is composed of heterogeneous hydrogen-bond distances and angles, and thus characterized as structurally ''distorted.''

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“…Three main modes are designated: the n 1 symmetric (OH) stretch near 3450 Dcm À1 , the n 2 H-O-H bending mode near 1640 Dcm À1 , and the n 3 water antisymmetric (OH) stretch mode near 3615 Dcm À1 . Walrafen (1964) also assigned four additional modes that yield weak Raman signals at 60, 175, 450, and 760 Dcm À1 associated with a cluster of a central water molecule surrounded by four hydrogen-bonded water molecules. The Raman spectrum of water is thus well known.…”

Section: The Raman Signal Of Sea Watermentioning

confidence: 99%

“…6. The Raman spectrum of water has been extensively studied (Walrafen, 1964). Three main modes are designated: the n 1 symmetric (OH) stretch near 3450 Dcm À1 , the n 2 H-O-H bending mode near 1640 Dcm À1 , and the n 3 water antisymmetric (OH) stretch mode near 3615 Dcm À1 .…”

Section: The Raman Signal Of Sea Watermentioning

confidence: 99%

Feasibility of Large-Scale Ocean Co2 Sequestration

Brewer¹,

Barry²

2004

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ABSTRACT:The past year has been one of continued high productivity and technical innovation for research conducted under support of this contract. We report here on the successful completion of development of a deep-ocean laser Raman spectrometer, and the use of this novel system for direct in situ measurement of the dissolution rate of CO 2 from a N 2 /CO 2 gas mixture at 300m ocean depth. We have carried out the deepest ever ocean CO 2 injection experiment at 3960m depth, and have observed the behavior of the plume of low pH/high CO 2 water emanating from this source. This was made possible by the design, construction, and operation of a novel flume to contain the liquid CO 2 and to force flow in a controlled manner over the liquid CO 2 surface. In carrying out this experiment we observed for the first time the extraordinarily rapid hydration kinetics of CO 2 with water at high pressure. This initial observation was later confirmed in a carefully controlled series of acid and CO 2 injection studies at varying depths. In carrying out this research we are aware of the environmental concerns, and we have been in the forefront of identifying the challenges resulting from the far greater quantities of CO 2 being passively absorbed from the atmosphere. This quantity now is approximately 1 million metric tons CO 2 per hour, and reasonable projections for the 21 st century project ocean pH changes of 0.3 or more by mid-century. The PIs have played a key role in organizing a major international meeting on this topic, and on reporting the results. We are now engaged in developing the novel techniques required to investigate this problem. INTRODUCTIONThe primary mechanism preventing very fast accumulation of CO 2 in the atmosphere is ocean absorption through the sea surface. This absorption, driven by the accumulated mean pCO 2 difference between air and sea, now proceeds at a rate of about 1 million metric tons CO 2 per hour. Thus ocean passive "disposal" of fossil fuel CO 2 is the primary greenhouse gas control technique used by all nations at all times, and the accumulated oceanic fossil fuel burden is now ≅ 500 billion tons CO 2 . In the few years that CO 2 is resident in the atmosphere it affects the planetary radiation balance and contributes to global warming. Thus some 25 years ago it was first suggested that direct injection of CO 2 into the deep ocean, thus bypassing the atmospheric disposal step with its attendant global warming, would be a useful greenhouse gas control technology. We have investigated this process in a series of studies carried out in part through the support of this award. These have involved creation of advanced experimental techniques for injection of CO 2 into the deep ocean, the measurement of the fate and behavior of the injected liquid, the formation and dissolution of a solid hydrate, and the environmental consequences of both direct and indirect CO 2 injection into the ocean. EXECUTIVE SUMMARYIn this report we detail research carried out in the period October 1, 2003 through Septemb...

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Raman Spectral Studies of Water Structure

Cited by 579 publications

References 23 publications

Electric-field-dependent empirical potentials for molecules and crystals: A first application to flexible water molecule adsorbed in zeolites

Electric-field-dependent empirical potentials for molecules and crystals: A first application to flexible water molecule adsorbed in zeolites

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

Feasibility of Large-Scale Ocean Co2 Sequestration

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