Far-infrared collision-induced absorption in compressed gaseous polar linear molecules: application to N2O

1988 ◽  
Vol 66 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Nguyen- Van-Thanh ◽  
I. Rossi
Keyword(s):  
Quadrupole Moment ◽  
Far Infrared ◽  
Pressure Data ◽  
Induced Absorption ◽  
A Value ◽  
Induced Dipole ◽  
Linear Molecules ◽  
Bimolecular Collisions ◽  
Integrated Intensities ◽  
Rotational Interaction

This paper deals with computations of the far-infrared collision-induced absorptions for polar linear molecules. We have considered Frost's theory for dipole- and quadrupole-induced dipole absorptions in bimolecular collisions, taking the anisotropy of the molecular polarizability into account. In addition to the induced rotational interaction, a translational effect may not be negligible. Detailed expressions for different contributions to the integrated intensities are reported for N2O. Using these calculated expressions and the moderately low pressure data, we have deduced a value for the quadrupole moment of N2O, [Formula: see text].

Collision-induced absorption in nitrogen at low temperatures

1985 ◽  
Vol 63 (5) ◽  
pp. 625-631 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
L. A. A. Read
Keyword(s):  
Quadrupole Moment ◽  
Laser System ◽  
Far Infrared ◽  
Microwave Cavity ◽  
Jones Potential ◽  
Induced Absorption ◽  
Line Shapes ◽  
Theoretical Predictions ◽  
Theoretical Line

The collision-induced absorption (CIA) spectrum for nitrogen has been measured in the spectral region below 360 cm−1 at 126, 149, 179, and 212 K. The measurements have been obtained using Fourier transform infrared (FTIR) techniques, a far infrared (FIR) laser system operating at 84.2 and 15.1 cm−1, and microwave cavity techniques. The experimental line shapes have been compared with the theoretical predictions of Joslin, based on Mori theory, and of Joslin and Gray, based on information theory alone. The data have been used to determine the quadrupole moment employing various intermolecular potentials. One Lennard–Jones potential has resulted in a quadrupole moment of 1.51 B, the value that was used in generating the theoretical line shapes. These results, when combined with our forthcoming measurements on nitrogen mixed with methane and argon, may be helpful in determining the role of CIA in calculating the opacity of some planetary atmospheres.

The quadrupole moment of cyanogen: a comparative study of collision-induced absorption in gaseous C2N2, CO2, and mixtures with argon

1986 ◽  
Vol 64 (11) ◽  
pp. 1475-1481 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Quadrupole Moment ◽  
Spectral Region ◽  
Gaseous Mixture ◽  
Far Infrared ◽  
Spectral Moments ◽  
A Value ◽  
Large Anisotropy ◽  
Experimental Values ◽  
Microwave Techniques ◽  
Good Agreement

The collision-induced spectra of C2N2 gas and a gaseous mixture of C2N2 and Ar at 298 K have been obtained in the spectral region below 120 cm−1 using far-infrared laser and microwave techniques as well as a Fourier-transform spectrometer. In addition, the collision-induced spectra of a gaseous mixture of CO2 and Ar are reported at temperatures of 233 and 298 K in the spectral region below 230 cm−1. The theoretical values for the spectral moments α1 and γ1 for CO2 are much smaller than the experimental values, as expected for a molecule with a relatively large quadrupole moment. However, for CO2–Ar mixtures, the agreement between the theoretically and experimentally determined spectral moments is relatively good, resulting in a value of 4.6 B for the quadrupole moment of CO2 instead of the generally accepted value of 4.3 B. The quadrupole moment of C2N2 is estimated to be 6.2 ± 0.4 B from our data and the theory for the spectral moments, if a correction is made for an overestimate of the quadrupole moment similar to that obtained for the CO2–Ar mixture. This value is considerably smaller than a previously reported calculated result of 9.0 B. Line-shape expressions based on information theory (IT6) do not yield good agreement with experiment, a result that is attributed to the large anisotropy of the molecules.

Far-infrared collision-induced absorption in some compressed gaseous halogenated methanes

1985 ◽  
Vol 63 (4) ◽  
pp. 475-478 ◽  
Author(s):  
Nguyen- Van-Thanh ◽  
I. Rossi
Keyword(s):  
Reasonable Agreement ◽  
Far Infrared ◽  
Molecular Polarizability ◽  
Experimental Literature ◽  
Induced Absorption ◽  
Bimolecular Collisions ◽  
Halogenated Methanes

Calculations of the collision-induced rotational and translational absorptions have been performed for seven pure halogenated methanes CH3F, CH3Cl, CF3H, CF3Cl, CF3Br, CCl3H, and CCl3F. We have considered the theory of Frost for multipole-induced dipolar absorption in bimolecular collisions taking the anisotropy of the molecular polarizability into account. The comparison with experimental literature data of CF3H and CF3Cl was reported; a reasonable agreement was obtained only for CF3Cl.

THE COLLISION-INDUCED FUNDAMENTAL AND FIRST OVERTONE BANDS OF OXYGEN AND NITROGEN

1966 ◽  
Vol 44 (5) ◽  
pp. 949-963 ◽  
Author(s):  
M. M. Shapiro ◽  
H. P. Gush
Keyword(s):  
Quadrupole Moment ◽  
Internuclear Distance ◽  
First Derivative ◽  
A Value ◽  
Integrated Intensities

The collision-induced rotation–vibration fundamental and first overtone bands of oxygen and nitrogen have been observed in the pure gas at pressures of a few atmospheres, and in mixtures of these gases with argon at pressures of a few tens of atmospheres. From the integrated intensities of the bands it is possible to deduce a value for the first derivative of the quadrupole moment with respect to internuclear distance; we find that |Q′| = 1.6ea0 for oxygen, and |Q′| = 0.95ea0 for nitrogen.

On the Theory of Collision-Induced Absorption in Rare Gas Mixtures

1971 ◽  
Vol 49 (7) ◽  
pp. 837-847 ◽  
Author(s):  
S. L. Brenner ◽  
D. A. McQuarrie
Keyword(s):  
Absorption Spectrum ◽  
Dipole Moment ◽  
Far Infrared ◽  
Gas Mixtures ◽  
Moment Function ◽  
Rare Gas ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Calculated Equilibrium

The observed far-infrared collision-induced absorption of helium–argon mixtures is used to determine the parameters in an induced-dipole moment function of the form[Formula: see text]It is shown that, with this form of μ(r), the values of the constants μo, ρ, and c7 that are necessary to fit the first two moments of the observed absorption contour are in disagreement with the available theoretical values of these constants. Possible explanations for this disagreement are discussed in the paper. Finally, it is shown that if μ(r) were known, it is possible to obtain an excellent representation of the entire absorption spectrum from a knowledge of only the first three moments, which are easily calculated equilibrium quantities.

Analysis of the far infrared spectrum of gaseous N2

1981 ◽  
Vol 59 (10) ◽  
pp. 1448-1458 ◽  
Author(s):  
J. D. Poll ◽  
J. L. Hunt
Keyword(s):  
Infrared Spectrum ◽  
Quadrupole Moment ◽  
Far Infrared ◽  
Spectral Moments ◽  
A Value ◽  
Dipole Parameters ◽  
Lineshape Function

The far infrared collision-induced spectrum of N2 gas at 300 and 124 K is analysed using an empirical lineshape function. The theory of the collision-induced spectrum of N2 is developed and expressions are derived for the first and second spectral moments in the cases of quadrupolar, hexadecapolar, and for L = 1 and L = 3 overlap induction. The spectra are then reconstructed with various combinations of these mechanisms in order to determine the best values and probable ranges of the quadrupole and hexadecapole moments and the strength of the overlap moments. We find an excellent fit for a value of the quadrupole moment that agrees with that found by Buckingham, QB = −(1.09 ± 0.05)ea02, with overlap dipole parameters λ1 = ± 1 × 10−3ea0, λ3 = 1 × 10−3ea0, and an effective hexadecapole moment Φ = −(10.4 ± 1)ea04.

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