Spectral lineshapes of collision-induced absorption (CIA) using isotropic intermolecular potential for N2-CH4

2021 ◽  
Vol 21 (4) ◽  
pp. 1063-1078
Author(s):  
M.S.A. El-Kader ◽  
G. Maroulis ◽  
T. Bancewicz
Keyword(s):  
Potential Model ◽  
Dipole Moments ◽  
Molecular Nitrogen ◽  
Intermolecular Potential ◽  
Gaseous Mixtures ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Different Temperatures ◽  
Experimental Absorption ◽  
Good Agreement

Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures are computed for gaseous mixtures of molecular nitrogen and methane using theoretical values for the induced dipole moments and intermolecular potential as input. Comparison with theoretical absorption spectra shows satisfactory agreement. An empirical model of the dipole moment which reproduces the experimental spectra and the first three spectral moments more closely than the fundamental theory, is also presented. Good agreement between computed and experimental absorption lineshapes is obtained when a potential model which is constructed from the thermophysical and transport properties is used.

Theoretical Calculation of the Rototranslational Collision-Induced Absorption (CIA) Spectra in O2–O2 Pairs

2016 ◽  
Vol 230 (8) ◽  
Author(s):  
Mohamed S. A. El-Kader
Keyword(s):  
Room Temperature ◽  
Interatomic Potential ◽  
Dipole Moments ◽  
Full Range ◽  
Quantum Mechanical ◽  
Fundamental Theory ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Good Agreement

AbstractQuantum mechanical lineshapes of collision-induced absorption (CIA) at room temperature are computed for gaseous molecular oxygen using theoretical values for induced dipole moments and new isotropic interatomic potential as input. Comparison with measured spectra of the rototranslational collision-induced absorption shows good agreement over the full range of frequencies. Empirical models of the dipole moment which reproduce the experimental spectra and the first two spectral moments more closely than the fundamental theory are also given. The quality of the present potential has been checked by comparing between calculated and experimental thermo-physical and transport properties over a wide temperature range, which are found to be in good agreement.

Temperature dependent collision-induced absorption in nitrogen

1984 ◽  
Vol 62 (4) ◽  
pp. 338-347 ◽  
Author(s):  
N. W. B. Stone ◽  
L. A. A. Read ◽  
A. Anderson ◽  
I. R. Dagg ◽  
W. Smith
Keyword(s):  
Close Agreement ◽  
Far Infrared ◽  
Intermolecular Potential ◽  
Fourier Transform Spectrometer ◽  
Fir Laser ◽  
Complete Spectrum ◽  
Temperature Dependent ◽  
Induced Absorption ◽  
Different Temperatures ◽  
Microwave Data

The collision-induced rotational translational spectrum of gaseous N2 has been measured in the temperature range 228–343 K at six different temperatures. The measurements were made with a Fourier transform spectrometer in the 25 to 360 cm−1 region and at 15.1 and 84.2 cm−1 with far infrared (FIR) laser. Previously obtained microwave data at 2.3 and 4.7 cm−1 have been used in defining the complete spectrum. Using a recently developed theory for quadrupolar-induced absorption, we find that the calculated quadrupole moment is independent of temperature and has a magnitude in close agreement with the recommended values of several other workers; i.e., Q = 1.46 B. The calculated value depends on the particular form of the intermolecular potential and this dependence is examined in some detail. A contribution to the absorption originating primarily from hexadecapolar and overlap induction has been observed in agreement with theoretical estimates and leads to an estimated value for the hexadecapolar moment [Formula: see text].

Lineshapes and dipole moments in collision-induced absorption

1981 ◽  
Vol 59 (10) ◽  
pp. 1544-1554 ◽  
Author(s):  
George Birnbaum ◽  
Michael S. Brown ◽  
Lothar Frommhold
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Empirical Models ◽  
Fundamental Theory ◽  
Potential Models ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Substantial Error ◽  
Argon Mixture ◽  
Helium Neon

Wave mechanical lineshapes of collision-induced absorption spectra are computed for binary mixtures of argon with helium, neon, and krypton using theoretical dipole moments as input. Comparison with measured spectra shows satisfactory agreement except for the neon–argon mixture, for which either theory or measurement is seen to be in substantial error. Empirical models of the collision-induced dipole moment which reproduce the experimental spectra more closely than the fundamental theory are also given. Best agreement between computed and experimental lineshapes is obtained when potential models which are accurate in the repulsive region are used.

Moment analysis in collision-induced absorption: Determination of a single parameter empirical model for the induced dipole moment of He-Ar gas mixtures

2021 ◽  
pp. 1-16
Author(s):  
M.S.A. El-Kader ◽  
G. Maroulis
Keyword(s):  
Dipole Moment ◽  
Empirical Model ◽  
Adjustable Parameter ◽  
Classical Physics ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Absorption Determination ◽  
Ar Gas ◽  
Good Agreement

We present a method for the construction of a one-adjustable-parameter empirical model for the induced dipole moment. The method is based on classical physics principles and relies on the first three spectral moments of the collision-induced absorption spectra at various temperatures and new interaction potentials. In this work it is applied to the spectra of He-Ar mixtures. Our values are in good agreement with the available ab initio data. The profiles calculated with these models at various temperatures are in excellent agreement with experiment.

Collision-induced absorption in gaseous mixtures of nitrogen and methane

1986 ◽  
Vol 64 (11) ◽  
pp. 1467-1474 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Far Infrared ◽  
Frequency Region ◽  
Theoretical Development ◽  
Gaseous Mixtures ◽  
Induced Absorption ◽  
Rotational Spectra ◽  
Theoretical Line ◽  
Microwave Techniques ◽  
Lower Frequency Region ◽  
Good Agreement

The collision-induced absorption spectra of nitrogen–methane gas mixtures have been measured in the spectral region below 400 cm−1 at four temperatures, namely, 212, 179, 149, and 126 K. The measurements have involved the use of Fourier-transform infrared and microwave techniques as well as a far-infrared laser operating at 84.2 and at 15.1 cm−1. These are compared with a theoretical line shape obtained from a convolution of free rotational spectra and a translational component as determined from information theory. The calculated spectra show good agreement with the experimental results only in the lower frequency region. An important feature of the theoretical development is that no adjustable parameters need be introduced.

SURFACE-INDUCED DIPOLE MOMENTS OF GALLIUM, INDIUM, AND TIN ON MOLYBDENUM SURFACE

1993 ◽  
Vol 07 (20) ◽  
pp. 1301-1306
Author(s):  
A. R. SAADAT
Keyword(s):  
Charge Transfer ◽  
Work Function ◽  
Field Emission ◽  
Dipole Moments ◽  
Liquid Gallium ◽  
Induced Dipole ◽  
Field Emission Microscopy ◽  
Emission Microscopy ◽  
Field Ion Microscope ◽  
Good Agreement

Liquid gallium (Ga), indium (In), and tin (Sn) were deposited on a molybdenum (Mo) surface. The surface-induced dipole moments of adsorbed adatoms Ga, In, and Sn on Mo were determined experimentally using field-ion and field-emission microscopy. The procedure of the experiment consisted of measuring the change in work function of Mo due to the adsorbed adatoms. The coverage of adatoms was obtained directly from a field-ion image of the surface using a field-ion microscope. The work function changes were obtained by measuring the field-emission currents and plotting the Fowler–Nordhiem curves. The results of this experiment for the induced dipole moments of Ga, In, and Sn adatoms were found to be 2.35 (D) for Ga, 2.39 (D) for In, and 2.25 (D) for Sn. These values are in good agreement with calculations using the charge transfer theory of chemisorption.

scholarly journals Experimental and Numerical Buckling Analyses of Laminated Composite Plates under Temperature Effects

2010 ◽  
Vol 19 (4) ◽  
pp. 096369351001900 ◽  
Author(s):  
Emin Ergun
Keyword(s):  
Composite Plate ◽  
Numerical Solutions ◽  
Laminated Composite ◽  
Composite Plates ◽  
Buckling Load ◽  
Fibre Reinforcement ◽  
Stacking Sequence ◽  
Laminated Composite Plates ◽  
Different Temperatures ◽  
Good Agreement

The aim of this study is to investigate, experimentally and numerically, the change of critical buckling load in composite plates with different ply numbers, orientation angles, stacking sequences and boundary conditions as a function of temperature. Buckling specimens have been removed from the composite plate with glass-fibre reinforcement at [0°]i and [45°]i (i= number of ply). First, the mechanical properties of the composite material were determined at different temperatures, and after that, buckling experiments were done for those temperatures. Then, numerical solutions were obtained by modelling the specimens used in the experiment in the Ansys10 finite elements package software. The experimental and numerical results are in very good agreement with each other. It was found that the values of the buckling load at [0°] on the composite plates are higher than those of other angles. Besides, symmetrical and anti-symmetrical conditions were examined to see the effect of the stacking sequence on buckling and only numerical solutions were obtained. It is seen that the buckling load reaches the highest value when it is symmetrical in the cross-ply stacking sequence and it is anti-symmetrical in the angle-ply stacking sequence.

Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 311-314 ◽  
Author(s):  
W.S. Loh ◽  
J.P.R. David ◽  
B.K. Ng ◽  
Stanislav I. Soloviev ◽  
Peter M. Sandvik ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Impact Ionization ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Different Temperatures ◽  
Ionization Coefficients ◽  
Increasing Temperature ◽  
The Impact ◽  
Good Agreement ◽  
Ionization Rates

Hole initiated multiplication characteristics of 4H-SiC Separate Absorption and Multiplication Avalanche Photodiodes (SAM-APDs) with a n- multiplication layer of 2.7 µm were obtained using 325nm excitation at temperatures ranging from 300 to 450K. The breakdown voltages increased by 200mV/K over the investigated temperature range, which indicates a positive temperature coefficient. Local ionization coefficients, including the extracted temperature dependencies, were derived in the form of the Chynoweth expression and were used to predict the hole multiplication characteristics at different temperatures. Good agreement was obtained between the measured and the modeled multiplication using these ionization coefficients. The impact ionization coefficients decreased with increasing temperature, corresponding to an increase in breakdown voltage. This result agrees well with the multiplication characteristics and can be attributed to phonon scattering enhanced carrier cooling which has suppressed the ionization process at high temperatures. Hence, a much higher electric field is required to achieve the same ionization rates.

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