Submillimetric and millimetric collision-induced absorption spectra in compressed gaseous nitrogen using very low-frequency optical source

1991 ◽  
Vol 69 (10) ◽  
pp. 1264-1272 ◽  
Author(s):  
R. Occelli ◽  
H. Chaaban ◽  
J. M. Moynault ◽  
R. Coulon ◽  
A. Balsamo
Keyword(s):  
Nonlinear Crystal ◽  
Relaxation Times ◽  
Low Frequency ◽  
Theoretical Models ◽  
Gaseous Nitrogen ◽  
Optical Source ◽  
Shape Model ◽  
Induced Absorption ◽  
Close Frequency ◽  
Absorption Measurements

A (sub)millimetric source is obtained by difference-frequency mixing in a nonlinear crystal. It allows investigation of spectral absorption between 4 and 40 cm−1 with a new two-beam spectroscopic mounting. The complete mounting is described. The measurement method is given in detail. Compressed gaseous nitrogen-induced absorption measurements are used to calculate relaxation times and spectral moments. Comparisons are made with other measurements in close frequency regions, and theoretical models and an empirical line-shape model.

Collision Induced Absorption in N2, CO2, and H2 at 2.3 cm−1

1975 ◽  
Vol 53 (18) ◽  
pp. 1764-1776 ◽  
Author(s):  
I. R. Dagg ◽  
G. E. Reesor ◽  
J. L. Urbaniak
Keyword(s):  
Microwave Absorption ◽  
Loss Factor ◽  
Relaxation Times ◽  
Virial Coefficients ◽  
Low Frequency ◽  
Frequency Region ◽  
Induced Absorption ◽  
Three Body ◽  
Initial Measurement

Collision induced microwave absorption is reported in pure N2, CO2, and H2 in the region of 2.3 cm−1. For N2 the results are taken at temperatures ranging from 208 to 333 K and at densities ranging from 50 to 300 amagat. The parts of the loss factor which are proportional to the square and the cube of the density are found to depend respectively on T−1.55±0.12 and T−2.56±0.44. These results are well explained by the theory which relates the virial coefficients and relaxation times to the loss factor. Both the two and three body relaxation times, τ2 and τ3 follow very closely a T−0.5 dependence. The ratio of τ2/τ3 is found to be 0.83. For CO2 the results are taken at temperatures ranging from 273 to 363 K and at densities ranging from 8 to 80 amagat. The parts of the loss factor which are proportional to the square and cube of the density depend respectively on T−3.08±0.05 and T−5.4±0.059. These results together with existing infrared results show that τ2 is nearly proportional to T−0.5 and the ratio τ2/τ3 is 0.91 at 296 K. An initial measurement is reported for collision induced absorption in H2. The results for all three gases have been compared to previously reported results in the low frequency region.

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

Collision Induced Microwave Absorption in N2, CH4, and N2–Ar, N2–CH4 Mixtures at 1.1 and 2.3 cm−1

1974 ◽  
Vol 52 (9) ◽  
pp. 821-829 ◽  
Author(s):  
I. R. Dagg ◽  
G. E. Reesor ◽  
J. L. Urbaniak
Keyword(s):  
Microwave Absorption ◽  
Quadrupole Moment ◽  
Linear Dependence ◽  
Relaxation Times ◽  
High Sensitivity ◽  
Higher Order ◽  
Induced Absorption ◽  
High Q ◽  
Order Dependence

Collision induced microwave absorption is reported in pure N2, N2–Ar, N2–CH4, mixtures, and in pure CH4 in the 35 and 70 GHz regions (1.1 and 2.3 cm−1) at a temperature of 22 °C. The measurements are accomplished using overmoded high Q cavities capable of pressurization of up to 5000 p.s.i.g. The apparatus and method are described. With the high sensitivity attained, the results in pure N2 from 30 → 250 amagat reveal terms in the square and cube of the density from which the relaxation times are calculated. The linear dependence on frequency of the collision induced absorption up to 2.3 cm−1 is established. Higher order dependence on the density is observed in the N2–Ar and N2–CH4 mixtures. Various estimates of the quadrupole moment of N2 are given, making use of earlier results in other frequency regions.

scholarly journals Determination of the Distribution of Relaxation Times by Means of Pulse Evaluation for Offline and Online Diagnosis of Lithium-Ion Batteries

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 36
Author(s):  
Erik Goldammer ◽  
Julia Kowal
Keyword(s):  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Sampling Rate ◽  
Relaxation Times ◽  
Low Frequency ◽  
Lithium Ion ◽  
Battery Management ◽  
Time Constants ◽  
Time Domain Data ◽  
Aging Study

The distribution of relaxation times (DRT) analysis of impedance spectra is a proven method to determine the number of occurring polarization processes in lithium-ion batteries (LIBs), their polarization contributions and characteristic time constants. Direct measurement of a spectrum by means of electrochemical impedance spectroscopy (EIS), however, suffers from a high expenditure of time for low-frequency impedances and a lack of general availability in most online applications. In this study, a method is presented to derive the DRT by evaluating the relaxation voltage after a current pulse. The method was experimentally validated using both EIS and the proposed pulse evaluation to determine the DRT of automotive pouch-cells and an aging study was carried out. The DRT derived from time domain data provided improved resolution of processes with large time constants and therefore enabled changes in low-frequency impedance and the correlated degradation mechanisms to be identified. One of the polarization contributions identified could be determined as an indicator for the potential risk of plating. The novel, general approach for batteries was tested with a sampling rate of 10 Hz and only requires relaxation periods. Therefore, the method is applicable in battery management systems and contributes to improving the reliability and safety of LIBs.

scholarly journals The challenging SED of AP Librae

2011 ◽  
Vol 7 (S284) ◽  
pp. 411-413 ◽  
Author(s):  
David Sanchez ◽  
Berrie Giebels ◽  
Pascal Fortin ◽  
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Low Frequency ◽  
Theoretical Models ◽  
Intermediate Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
Broad Band Emission ◽  
Band Emission ◽  
Bl Lac

AbstractMatching the broad-band emission of active galaxies with the predictions of theoretical models can be used to derive constraints on the properties of the emitting region and to probe the physical processes involved. AP Librae is the third low frequency peaked BL Lac (LBL) detected at very high energy (VHE, E>100GeV) by an Atmospheric Cherenkov Telescope; most VHE BL Lacs (34 out of 39) belong to the high-frequency and intermediate-frequency BL Lac classes (HBL and IBL). LBL objects tend to have a higher luminosity with lower peak frequencies than HBLs or IBLs. The characterization of their time-averaged spectral energy distribution is challenging for emission models such as synchrotron self-Compton (SSC) models.

The low frequency motions of solvated Mn(ii) and Ni(ii) ions and their halide complexes

2014 ◽  
Vol 16 (45) ◽  
pp. 25101-25110 ◽  
Author(s):  
Vinay Sharma ◽  
Fabian Böhm ◽  
Gerhard Schwaab ◽  
Martina Havenith
Keyword(s):  
Low Frequency ◽  
Hydration Water ◽  
P Concentration ◽  
Halide Complexes ◽  
Absorption Measurements

Concentration dependent THz/FIR absorption measurements allow determination of individual solvated ion resonances and their influence on the hydration water spectrum.

Effects of director rotation relaxation on viscoelastic wave dispersion in nematic elastomer beams

2018 ◽  
Vol 24 (4) ◽  
pp. 1103-1115 ◽  
Author(s):  
Dong Zhao ◽  
Ying Liu
Keyword(s):  
Wave Motion ◽  
Relaxation Times ◽  
Low Frequency ◽  
Wave Dispersion ◽  
Frequency Limit ◽  
Anisotropic Parameter ◽  
Acoustic Design ◽  
Phase Velocities ◽  
Nematic Elastomer ◽  
Viscoelastic Wave

In this paper, the transverse wave dispersion in a nematic elastomer (NE) Timoshenko beam is studied by considering anisotropy and viscoelasticity of NEs in the low frequency limit. Firstly, the characteristic equations of wave motion in an NE beam are derived, and then numerically solved to obtain the corresponding phase velocities and attenuation factors. The influences of anisotropic parameter, director rotation and rubber relaxation times on the wave dispersion in an NE beam are discussed. Results show that unlike the situation in general isotropic viscoelastic beam, non-classical viscoelastic wave dispersion is found in NE beams. Geometric dispersion is restrained with the vanishing of cut-off frequencies for shear waves due to director rotation relaxation of NEs. This unique property promises prospective applications of NE beams in optic or acoustic design.

Time Domain Zero Field NMR and NQR

1986 ◽  
Vol 41 (1-2) ◽  
pp. 440-444 ◽  
Author(s):  
A. Bielecki ◽  
D. B. Zax ◽  
A. M. Thayer ◽  
J. M. Millar ◽  
A. Pines
Keyword(s):  
Time Domain ◽  
Relaxation Times ◽  
Low Frequency ◽  
High Sensitivity ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Zero Field ◽  
Spin Lattice ◽  
Field Cycling ◽  
The Time Domain

Field cycling methods are described for the time domain measurement of nuclear quadrupolar and dipolar spectra in zero applied field. Since these techniques do not involve irradiation in zero field, they offer significant advantages in terms of resolution, sensitivity at low frequency, and the accessible range of spin lattice relaxation times. Sample data are shown which illustrate the high sensitivity and resolution attainable. Comparison is made to other field cycling methods, and an outline of basic instrumental requirements is given.

scholarly journals Parametric Nonlinear Locator

2018 ◽  
Vol 155 ◽  
pp. 01010 ◽  
Author(s):  
Vladimir Antipov ◽  
Sergey Shipilov
Keyword(s):  
Low Frequency ◽  
Electrical Contacts ◽  
Radio Waves ◽  
Design Features ◽  
Frequency Modulator ◽  
Non Linear ◽  
Close Frequency

The device relates to the field of radar techniques for locating or objects detecting using reflection or reradiation of radio waves. This device can be used to detect and identify the objects containing non-linear electrical contacts. The non-linear radar contains two sources of signals that generate the signals in close frequency rangers, and a signal combining scheme associated with the antenna. The source of the first signal is provided with a low-frequency modulator. A vector reflectometer is included between the source of the second signal and the signal combining circuit. The design is simplified and the detectability of the non-linear radar is improved due to these design features.

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