DIELECTRIC RELAXATION IN LIQUIDS: II. ISOMERIC PENTANEDIOLS

1961 ◽  
Vol 39 (11) ◽  
pp. 2139-2154 ◽  
Author(s):  
D. W. Davidson
Keyword(s):  
Hydrogen Bonding ◽  
High Frequency ◽  
Low Temperatures ◽  
Dipole Moments ◽  
Frequency Dispersion ◽  
Liquid Structure ◽  
Dielectric Constants ◽  
Oh Groups ◽  
High Frequencies ◽  
Static Dielectric Constants

For five pentanediols the infrared spectra, the dipole moments, and the static dielectric constants show an increasing degree of internal hydrogen bonding with increasing proximity of the OH groups. The dielectric dispersion loci at low temperatures are skewed arcs over most of the dispersion range. Values of the parameter β decrease from ca. 1 to 0.55 in the series 1,5-, 1,4-, 1,2-, 2,4-, and 2,3-pentanediol, which is also the order of increasing relaxation time τ0 at low temperatures. Increased τ0 is associated with increased irregularity of intermolecular hydrogen bonding, an effect which supports the view that relaxation proceeds by a co-operative mechanism which is facilitated by regularity in the liquid structure. At temperatures of "structural relaxation", values of log τ0 are linear in (T–T∞)−1; the proportionality constants, but not the T∞'s, are the same for all five diols.The experimental behavior at relatively high frequencies departs from both the skewed-arc and Glarum equations, although less from the latter. These departures are compared with the high frequency dispersion regions in n-propanol.

THE LOW-FREQUENCY DIELECTRIC PROPERTIES OF ETHYLENE OXIDE AND ETHYLENE OXIDE HYDRATE

1963 ◽  
Vol 41 (6) ◽  
pp. 1424-1434 ◽  
Author(s):  
D. W. Davidson ◽  
G. J. Wilson
Keyword(s):  
Ethylene Oxide ◽  
High Frequency ◽  
Low Temperatures ◽  
Low Frequency ◽  
Dielectric Constants ◽  
Water Molecules ◽  
Kcal Mole ◽  
Absorption Region ◽  
Experimental Values ◽  
Static Dielectric Constants

The static dielectric constant of liquid ethylene oxide has been measured between 158 and 286 °K. The hydrate of ethylene oxide exhibits a dispersion–absorption region characterized by static dielectric constants about one-third as large as those of ice and by relatively large "high-frequency" dielectric constants (ε1 = 7.5 at 0 °C). This region may be approximately described as a circular arc locus, but may be represented somewhat better by a superposition of two (or three) semicircular dispersions. In either case, the activation energy for the relaxation of water molecules, to which this region is ascribed, is ca. 6.7 kcal/mole, except at low temperatures, where it becomes smaller. Experimental values of ε1 agree roughly with those calculated for comparatively rapid orientation of ethylene oxide molecules in the cavities of the hydrate. Such orientation may account for absorption maxima observed at 11 Mc/sec and above 100 Mc/sec at 90 °K.

scholarly journals Review of the Effects of the Influence of External Vibrations on the Freezing Point of Water

2020 ◽  
Vol 320 ◽  
pp. 00032
Author(s):  
Emmanuele Adorni ◽  
Mikhail Ivanov ◽  
Roberto Revetria
Keyword(s):  
Liquid State ◽  
High Frequency ◽  
Low Temperatures ◽  
Freezing Point ◽  
Tap Water ◽  
Distilled Water ◽  
High Frequencies ◽  
High Frequency Vibrations

With this paper we want to provide a first glance at some of those researches that studied how to lower the freezing point of water below the ordinarily point by using external vibrations. All the researches started with experiments on distilled water (obtained with different methodology depending on the experiment) and then moving forward to experiments on tap water (contaminated with a known amount of substances). In all cases, methods to bring the samples to an undercooled state were applied at first. Through high frequency vibrations it has been studied how the formation of ice in a vessel of water can be controlled mainly thanks to the development of the phenomenon of cavitation in the water. By increasing the pressure in certain zones of the samples it was possible to study the phenomena linked to water freezing. Some experiments showed how, even with high frequencies, it is still difficult to obtain reliable results on the topic of keeping the water in a liquid state in conditions of low temperatures and with vibrations applied to the fluid.

scholarly journals Optical properties and electronic polarizability of boron-antimonide semiconductor

2017 ◽  
Vol 5 (2) ◽  
pp. 43 ◽  
Author(s):  
Salah Daoud ◽  
Abdelhakim Latreche
Keyword(s):  
Optical Properties ◽  
High Frequency ◽  
Theoretical Data ◽  
Dielectric Constants ◽  
Electronic Polarizability ◽  
Micro Hardness ◽  
Plasmon Energy ◽  
Empirical Formulas ◽  
Electronegativity Difference ◽  
Static Dielectric Constants

The high-frequency and static dielectric constants, the reflex index, the total optical electronegativity difference, the bulk modulus, the micro-hardness, the plasmon energy and the electronic polarizability of cubic zincblende boron-antimonide semiconductor have been estimated by using some empirical formulas. These parameters are analyzed by comparing them against the available experimental and theoretical data. In general, our obtained results agree well with other theoretical data from the literature.

scholarly journals Quasi-linear correlation between high-frequency and static die-lectric constants in II-VI and III-V semiconductors

2016 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Salah Daoud ◽  
Abdelhalim Bencheikh ◽  
Laarbi Belagraa
Keyword(s):  
Linear Regression ◽  
Linear Relationship ◽  
Linear Correlation ◽  
High Frequency ◽  
Null Hypothesis ◽  
Alkali Halides ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Quantitative Form ◽  
Static Dielectric Constants

A quantitative form of the linear correlation between the high-frequency and static dielectric constants in ANB8-N (N = 2, 3) tetrahedrally coordinated semiconductor materials, and also in I-VII group alkali halides was studied. So, a quasi-linear relationship was found between the high-frequency and the static dielectric constants for some selected II-VI (ZnS, ZnSe, ZnTe and CdTe) and III-V (AlP, AlAs, AlSb,….etc) cubic zincblende type materials, in the other side a weak uphill linear relationship has been found in the case of I-VII (LiF, NaF, LiCl,….etc) group alkali halides compounds. In the case of II-VI and III-V cubic zincblende semiconductors, the linear regression is established with a correlation coefficient ( ) of about 0.98. The significance of the linear regression is given as the probability P <0.0001 of the null hypothesis.

Dielectric properties of the hydrates of argon and nitrogen

1968 ◽  
Vol 46 (10) ◽  
pp. 1673-1681 ◽  
Author(s):  
S. R. Gough ◽  
E. Whalley ◽  
D. W. Davidson
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Dielectric Constants ◽  
Water Molecules ◽  
Circular Arc ◽  
Circular Arcs ◽  
In Series ◽  
Temperature And Pressure ◽  
Water Lattice ◽  
Static Dielectric Constants

The dielectric relaxation of water in the structure I clathrate hydrates of argon and nitrogen was studied over a range of temperature and pressure. Hydrates were slowly grown at pressures of 1 to 2 kbar in a coaxial cell enclosed in a pressure vessel. The complex permittivity loci resemble circular arcs with static dielectric constants of ~56 at 0 °C and high-frequency dielectric constants of 2.85 ± 0.05. Relaxation near 0 °C is about as slow as in ice I, but activation energies and entropies are much smaller. Formation of Bjerrum defects probably takes place preferentially near the occasional sites at which argon and nitrogen molecules have replaced water molecules in the lattice. The much faster relaxations found previously in the isostructural hydrates of ethers arise from orientational defects induced in the water lattice by the encaged molecules, a small proportion of which may form hydrogen bonds with water. The effect of small gaps in series with samples showing circular-arc dispersion behavior was evaluated.

THE DIELECTRIC BEHAVIOR AT LOW TEMPERATURES OF SEVERAL GASES ADSORBED UPON POROUS VYCOR GLASS

1962 ◽  
Vol 40 (1) ◽  
pp. 92-103 ◽  
Author(s):  
I. D. Chapman ◽  
R. McIntosh
Keyword(s):  
Low Temperatures ◽  
Molecular Layer ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Ethyl Chloride ◽  
Threshold Temperature ◽  
Hydroxyl Groups ◽  
Vycor Glass ◽  
Oh Groups ◽  
Adsorbed Phase

The complex dielectric constants of several systems comprising a gas adsorbed on Vycor glass have been measured at temperatures between 0 °C and −180 °C and frequencies between 3 kc/sec and 4 Mc/sec. The real and imaginary parts of the dielectric constant of the adsorbed phase have been computed. Loss maxima occurring at low temperatures are observed for some of the matter in the monolayer and are assumed to be due to complexes formed between the gas first admitted and hydroxyl groups which are covalently attached to the surface of the glass. The complexes may be considered either as dipoles having two equilibrium positions, or as highly damped oscillators. Ethyl chloride adsorbed in the first molecular layer and not bonded to OH behaves as an oscillatory system for which no loss is observed in the frequency and temperature ranges studied. Ethyl chloride adsorbed in the multilayers behaves similarly but shows a slightly greater temperature coefficient of ε′. Both these types of adsorbed ethyl chloride interact with the complexes and reduce the threshold temperature at which loss is observed in the complex. Methyl chloride interacts with OH groups in a similar fashion, but n-butane does not.

scholarly journals Rheology of rounded mammalian cells over continuous high-frequencies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gotthold Fläschner ◽  
Cosmin I. Roman ◽  
Nico Strohmeyer ◽  
David Martinez-Martin ◽  
Daniel J. Müller
Keyword(s):  
High Frequency ◽  
Mammalian Cells ◽  
Mechanical Response ◽  
Cell Mass ◽  
Low Frequency ◽  
Mass Measurements ◽  
High Frequencies ◽  
Polymer Relaxation ◽  
Continuous Frequency ◽  
Rheological Experiments

AbstractUnderstanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

The chemistry of aliphatic unconjugated nitramines. II. Intramolecular properties and crystal packing

1969 ◽  
Vol 22 (12) ◽  
pp. 2505 ◽  
Author(s):  
J Stals
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Packing ◽  
Dipole Moments ◽  
Molecular Crystals ◽  
Bond Orders ◽  
Bond Energies ◽  
Electric Dipole Moments ◽  
Charge Distributions ◽  
Hydrogen Bonding Interactions ◽  
Vb Structures

The VESCF(BJ)-MO electric dipole moments, molecular ionization potentials, electronic bond energies, charge distributions, and bond orders for nitramide, N-methylnitramine, and s- and as-N,N- dimethylnitramines are reported. The packing of nitramide, RDX, and HNX in their molecular crystals is rationalized in terms of electrostatic and hydrogen-bonding interactions. Simple VB structures do not readily predict their calculated MO charge distributions and bond orders.

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