Dielectric dispersion in pure polar liquids at very high radio-frequencies II. Relation of experimental results to theory

1952 ◽  
Vol 213 (1115) ◽  
pp. 473-492 ◽  
Keyword(s):  
Relaxation Time ◽  
Viscous Flow ◽  
Frequency Factor ◽  
Dielectric Dispersion ◽  
Resonance Absorption ◽  
Millimetre Wave ◽  
Polar Liquids ◽  
Single Relaxation Time ◽  
Observed Behaviour ◽  
Very High

The results of the measurements at centimetre and millimetre wave-lengths on the dielectric properties of water, methyl alcohol and ethyl alcohol described in part I are analyzed. There is no evidence that, for any of these liquids, more than a single relaxation time as a function of temperature is required to account for the dispersion arising from dipole rotation. It is suggested that the observed behaviour of the two alcohols at wave-lengths near to 1 cm, which appears not to conform with the hypothesis of a single relaxation time, is in fact the consequence of resonance absorption. If it is supposed that in dipole rotation and viscous flow the molecules have to surmount potential energy barriers, then it appears that, in each of the liquids examined, the heights of the barriers concerned in the two processes are identical; but the ‘frequency factor’ associated with such processes is much larger for viscous flow than for dipole rotation.

Dielectric dispersion in pure polar liquids at very high radio frequencies - III.The effect of electrolytes in solution

1952 ◽  
Vol 214 (1119) ◽  
pp. 531-545 ◽  
Keyword(s):  
Sodium Chloride ◽  
Ionic Conductivity ◽  
Aqueous Solutions ◽  
Methyl Alcohol ◽  
Dielectric Dispersion ◽  
Basic Theory ◽  
Polar Liquids ◽  
Polar Dielectric ◽  
Radio Frequencies ◽  
Very High

A description is given of measurements at millimetre and centimetre wave-lengths of absorption in electrolytic solutions, up to concentrations of about 3 normal, with water and methyl alcohol as solvents. The observations are analyzed in terms of Debye’s basic theory of dispersion in a polar dielectric, and it is shown what modifications to the theory are necessary to take account of the ionic conductivity produced by an electrolyte. Measure­ments on aqueous solutions of sodium chloride are discussed in relation to Hückel’s theory of electrolytic solutions.

Dielectric dispersion in pure polar liquids at very high radio-frequencies I. Measurements on water, methyl and ethyl alcohols

1952 ◽  
Vol 213 (1114) ◽  
pp. 400-408 ◽  
Keyword(s):  
Refractive Index ◽  
Absorption Coefficient ◽  
Radio Frequency ◽  
Freezing Point ◽  
Dielectric Dispersion ◽  
Wave Guide ◽  
Electrical Characteristics ◽  
Polar Liquids ◽  
Radio Frequency Energy ◽  
Very High

The results are given of some measurements of the absorption coefficient and refractive index of water, methyl and ethyl alcohols at wave-lengths of 6·2 mm, 1·24 cm and 3·21 cm over the temperature range —10 to 50°C, including some observations on water in the supercooled state. The method used is based upon the fact that the rate of attenuation of radio-frequency energy along a wave-guide filled with the liquid is dependent upon both the absorption coefficient and the refractive index when the guide is operated near to the cut-off condition. The electrical characteristics of water vary in a continuous manner through the normal freezing-point of 0°C down to at least —8°C. The measurements indicate that both alcohols, like water, have relatively high atomic polarizations.

Dielectric dispersion in viscous polar liquids

1956 ◽  
Author(s):  
J. W. Winslow ◽  
R. J. Good ◽  
P. E. Berghausen
Keyword(s):  
Dielectric Dispersion ◽  
Polar Liquids

Light-induced reversible ionization of tetramethylphenylenediamine in an inorganic polymer of n-butyl orthotitanate

1988 ◽  
Vol 66 (8) ◽  
pp. 1931-1935
Author(s):  
Hisashi Ueda ◽  
Masahiro Kaise
Keyword(s):  
Relaxation Time ◽  
Electron Spin Resonance ◽  
Visible Light ◽  
Relative Intensity ◽  
Hyperfine Splitting ◽  
Resonance Absorption ◽  
Spin Quantum ◽  
Spin Quantum Number ◽  
Spin Resonance ◽  
Intensity Ratios

n-Butyl orthotitanate, BT, polymerized in tetrahydrofuran, if irradiated by visible light, gives a new electron spin resonance absorption that is not found before irradiation. In the present work, three different polymers of BT were synthesized by adding tetramethyl phenylenediamine (TMPD), dimethyl phenylenediamine (DMPD), or phenylenediamine (PD), to the solution of BT. The polymers thus prepared were tested to see if they give a new esr signal when irradiated by visible light. The polymer to which 1 mol% of TMPD was added gave TMPD•+ when irradiated by visible light, but the TMPD•+ signal decayed after the irradiation was discontinued. This change, therefore, is reversible. The resonant position of every hyperfine splitting line of the TMPD•+ found in this polymer coincided with that of TMPD•+ in solution, but the relative intensity ratios and the line width of each line depended on the nuclear spin quantum number of the coupling nuclei. This can be interpreted by the restricted rotational motion of TMPD•+ in the polymer matrix. The contribution of the non-diagonal term to the spin relaxation time would explain this phenomenon. In the case of the polymer to which DMPD was added, a small amount of DMPD•+ seemed to be formed, but no radical was detected in the case of the polymer to which PD was added.

scholarly journals Molecular Association of Tetramethylurea and Chlorobenzene Molecules in Microwave Frequency Range

2010 ◽  
Vol 65 (10) ◽  
pp. 854-858
Author(s):  
Vimal Sharma ◽  
Nagesh Thakur
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Viscous Flow ◽  
Relaxation Process ◽  
Binary Mixtures ◽  
Variation Method ◽  
Dielectric Relaxation Time ◽  
Flow Process ◽  
Dielectric Relaxation Process ◽  
Energy Parameters

The dielectric constant ε´ and dielectric loss ε´´ of the binary mixtures of tetramethylurea (TMU) and chlorobenzene (CB) have been calculated at 9.883 GHz by using standard standing microwave techniques. Gopalakrishna’s single frequency concentration variation method has been used to calculate dipole moment μ and dielectric relaxation time τ for different mole fractions of TMU in the binary mixture at different temperatures of 25 °C, 30 °C, 35 °C, and 40 °C. The variation of dielectric relaxation time with the mole fraction of TMU in the whole concentration range of the binary mixtures was found to be non-monotonic. The solute-solute and solute-solvent type of molecular associations may be proposed based upon above observations. Using Eyring rate equations the energy parameters ΔH, ΔF, and ΔS for the dielectric relaxation process and the viscous flow process have been calculated at the given temperatures. It is found from the comparison of energy parameters that, just like the viscous flow process, the dielectric relaxation process can also be treated as a rate process.

The dielectric behaviour of dipolar mixtures I: chlorobenzene–nitrobenzene mixtures

1986 ◽  
Vol 64 (11) ◽  
pp. 1534-1536 ◽  
Author(s):  
F. F. Hanna ◽  
K. N. Abdel-Nour ◽  
A. M. Ghoneim
Keyword(s):  
Relaxation Time ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Dielectric Behaviour ◽  
Dilute Solutions ◽  
Single Relaxation Time ◽  
Microwave Region ◽  
Dielectric Absorption

The dielectric absorption of dilute solutions of nitrobenzene, chlorobenzene, and their mixtures in cyclohexane and Decalin® have been measured in the microwave region at three temperatures between 20 and 40 °C. The relaxation times and thermodynamic parameters are determined. A single relaxation time is found for the mixtures, and the results are discussed.

Simulation of Flow Past a Square Cylinder by Parallel Lattice Boltzmann Method using Multi-Relaxation-Time Scheme

2006 ◽  
Vol 22 (1) ◽  
pp. 35-42 ◽  
Author(s):  
J.-S. Wu ◽  
Y.-L. Shao
Keyword(s):  
Relaxation Time ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Numerical Results ◽  
Channel Height ◽  
Blockage Ratio ◽  
Square Cylinder ◽  
Single Relaxation Time ◽  
Boltzmann Method

AbstractThe flows past a square cylinder in a channel are simulated using the multi-relaxation-time (MRT) model in the parallel lattice Boltzmann BGK method (LBGK). Reynolds numbers of the flow are in the range of 100 ∼ 1,850 with blockage ratio, 1/6, of cylinder height to channel height, in which the single-relaxation-time (SRT) scheme is not able to converge at higher Reynolds numbers. Computed results are compared with those obtained using the SRT scheme where it can converge. In addition, computed Strouhal numbers compare reasonably well with the numerical results of Davis (1984).

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