Librational Modes of Crystal Water in Hydrated Solids

Tayal, V. P.; Srivastava, Bipin K.; Khandelwal, D. P.; Bist, H. D.

doi:10.1080/05704928008081709

Cited by 85 publications

(43 citation statements)

References 201 publications

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“…Librational modes can be described in terms of motion about the three principal axes of water: wagging, twisting, and rocking. These modes are highly dependent on the local environment and ordering of water [69,70] and sharp librational features have been observed for crystal water in hydrated solids [71]. Therefore, the variations in librational mode frequencies in Figure 5b can be attributed to localized H-bonding and steric restrictions caused by nanoscale confinement.…”

Section: Number Of Hydrogen Bonds (%)mentioning

confidence: 84%

Molecular Dynamics Simulations of Hydroxyapatite Nanopores in Contact with Electrolyte Solutions: The Effect of Nanoconfinement and Solvated Ions on the Surface Reactivity and the Structural, Dynamical, and Vibrational Properties of Water

et al. 2017

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Hydroxyapatite, the main mineral phase of mammalian tooth enamel and bone, grows within nanoconfined environments and in contact with aqueous solutions that are rich in ions. Hydroxyapatite nanopores of different pore sizes (20 Å ≤ H ≤ 110 Å, where H is the size of the nanopore) in contact with liquid water and aqueous electrolyte solutions (CaCl 2 (aq) and CaF 2 (aq)) were investigated using molecular dynamics simulations to quantify the effect of nanoconfinement and solvated ions on the surface reactivity and the structural and dynamical properties of water. The combined effect of solution composition and nanoconfinement significantly slows the self-diffusion coefficient of water molecules compared with bulk liquid. Analysis of the pair and angular distribution functions, distribution of hydrogen bonds, velocity autocorrelation functions, and power spectra of water shows that solution composition and nanoconfinement in particular enhance the rigidity of the water hydrogen bonding network. Calculation of the water exchange events in the coordination of calcium ions reveals that the dynamics of water molecules at the HAP-solution interface decreases substantially with the degree of confinement. Ions in solution also reduce the water dynamics at the surface calcium sites. Together, these changes in the properties of water impart an overall rigidifying effect on the solvent network and reduce the reactivity at the hydroxyapatite-solution interface. Since the process of surface-cation-dehydration governs the kinetics of the reactions occurring at mineral surfaces, such as adsorption and crystal growth, this work shows how nanoconfinement and solvation environment influence the molecular-level events surrounding the crystallization of hydroxyapatite.

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Section: Number Of Hydrogen Bonds (%)mentioning

confidence: 84%

Molecular Dynamics Simulations of Hydroxyapatite Nanopores in Contact with Electrolyte Solutions: The Effect of Nanoconfinement and Solvated Ions on the Surface Reactivity and the Structural, Dynamical, and Vibrational Properties of Water

et al. 2017

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“…The intermolecular librations of H 2 O occur in the range from 500 to 1100 cm À1 (Denisov et al, 1997;Beta et al, 2004;Eisenberg & Kauzmann, 2005), but their actual positions, shape, and intensity depend strongly on the molecular environment of the water (e.g. Tayal et al, 1980), which makes INS a very useful probe for examining the structural and dynamical properties of water within porous systems like opals. In fact, most of the frequency region below 1500 cm À1 has received scant attention in optical spectroscopic studies to date because of the weak contributions from water to the optical spectrum and the dominance of the silica scattering, All investigated opals exhibit a range in pore sizes and many of the smaller pores are not connected by channels.…”

Section: Discussionmentioning

confidence: 99%

Ordering of water in opals with different microstructures

Eckert¹,

Gourdon²,

Jacob³

et al. 2015

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Opal has long fascinated scientists. It is one of the few minerals with an amorphous structure, and yet, compared to silica glass, it is highly organized on the mesoscale. By means of inelastic neutron scattering (INS), we could document that in four samples of opal at low temperature an ice-like structure of water is present, with details depending on microstructural characteristics. While FTIR spectra for all samples are nearly identical and thus not very informative, INS shows clear differences, highlighting the significance of microstructures. Neutron diffraction at 100 K on one of the opal samples provides evidence for crystalline cubic ice.

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“…Hindered rotations are also called librations and the three librational modes of water molecules are denoted as: rocking, wagging and twisting. Bands from librational modes in the vibrational spectra are often found in the region between 1000 cm -1 and 300 cm -1 [30]. As a rule, the bands from these modes are with higher intensity in the IR spectra than in the Raman spectra (see e.g.…”

Section: External Vibrations Of Water Moleculesmentioning

confidence: 99%

“…Hindered translations of water molecules that are not coordinated to a metal usually appear below 300 cm -1 , whereas for coordinated water molecules they appear in the region between 500 and 300 cm -1 [25]. The librational modes have been reviewed and results from systematic studies are published in the works of Falk and Knop [24], Tayal et al [30] and Lutz [27]. In spite of the thorough studies, there are still unresolved questions related to the nature of the three librational modes, their expected frequencies, criteria for their exact assignment as well as the expected intensites of the bands from the librations of the water molecules in the IR and Raman spectra.…”

Section: External Vibrations Of Water Moleculesmentioning

confidence: 99%

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VERY LOW H–O–H BENDING FREQUENCIES. VI. VIBRATIONAL SPECTRA OF CdCl2·H2O

Stefov¹,

Najdoski²,

Engelen³

et al. 2017

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The infrared and Raman spectra of CdCl 2 ·H 2 O as well as those of a series of its partially deuterated analogues were recorded at room and at liquid-nitrogen temperature (RT and LNT, respectively). The combined results from the analysis of the spectra were used to assign the observed bands. In the difference IR spectrum of the compound with low deuterium content (≈ 4 % D) recorded at RT, one broad bands is observed at around 2590 cm -1 while in the LNT spectrum two bands appear (at 2584 cm -1 and 2575 cm -1 ). The appearance in the LNT spectrum of these two bands which are due to the stretching OD modes of the isotopically isolated HDO molecules points to the existance of two crystallographically different hydrogen bonds and is in accordance with the structural data for this compound. In the LNT infrared and Raman spectra of the protiated compound, one band, at 1583 cm -1 , is observed in the region of the bending НОН vibrations with a frequency that is decreasing with lowering the temperature. An interesting finding related to this band is that its frequency is lower than that for the water molecule in the gas phase (1594 cm -1 ). In the RT and LNT IR spectra, only one strong band (at 560 cm -1 ) is observed in the region of the librations of water molecules (700 cm -1 -400 cm -1).

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Librational Modes of Crystal Water in Hydrated Solids

Cited by 85 publications

References 201 publications

Molecular Dynamics Simulations of Hydroxyapatite Nanopores in Contact with Electrolyte Solutions: The Effect of Nanoconfinement and Solvated Ions on the Surface Reactivity and the Structural, Dynamical, and Vibrational Properties of Water

Molecular Dynamics Simulations of Hydroxyapatite Nanopores in Contact with Electrolyte Solutions: The Effect of Nanoconfinement and Solvated Ions on the Surface Reactivity and the Structural, Dynamical, and Vibrational Properties of Water

Ordering of water in opals with different microstructures

VERY LOW H–O–H BENDING FREQUENCIES. VI. VIBRATIONAL SPECTRA OF CdCl2·H2O

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