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.

The collision-induced translational spectrum of CF4–He gas mixtures

1980 ◽  
Vol 58 (6) ◽  
pp. 836-839 ◽  
Author(s):  
A. D. Afanasev ◽  
M. O. Bulanin ◽  
M. V. Tonkov
Keyword(s):  
Dipole Moment ◽  
Infrared Spectrum ◽  
Far Infrared ◽  
Gas Mixtures ◽  
Moment Function ◽  
Band Shape ◽  
Induced Dipole

The collision-induced far infrared spectrum of CF4–He gas mixtures was measured at 213 K. It is shown that the observed enhancement of the absorption represents the translational spectrum induced by isotropic overlap forces. The band shape calculations are consistent with the assumption that the collision-induced dipole moment varies exponentially with intermolecular separation, and the parameters of the dipole moment function have been determined.

COLLISION-INDUCED ABSORPTION OF COMPRESSED GASES IN THE FAR INFRARED, PART I

1965 ◽  
Vol 43 (5) ◽  
pp. 729-750 ◽  
Author(s):  
D. R. Bosomworth ◽  
H. P. Gush
Keyword(s):  
Fourier Analysis ◽  
Infrared Absorption ◽  
Michelson Interferometer ◽  
Far Infrared ◽  
Gas Mixtures ◽  
Experimental Techniques ◽  
Rare Gas ◽  
Absorption Coefficients ◽  
Induced Absorption ◽  
Separate Paper

A study is being made of the far infrared absorption occurring in compressed rare-gas mixtures, and compressed homonuclear diatomic gases. The region investigated lies between 20 and 400 cm−1. The spectra are obtained from the Fourier analysis of interferograms produced by a dynamic Michelson interferometer. It is possible to obtain accurate absolute absorption coefficients for broad bands using this method provided care is exercised in the analysis of the interferograms. The necessary precautions are discussed in detail. The precision of the method obtained in practice is demonstrated using the far infrared bands of hydrogen and nitrogen as examples. Only the experimental techniques are discussed in this paper; the detailed results follow in a separate paper.

Far-infrared collision-induced absorption in rare gas mixtures: Quantum and semi-classical calculations

2014 ◽  
Vol 140 (15) ◽  
pp. 154302 ◽  
Author(s):  
Ilya Buryak ◽  
Lothar Frommhold ◽  
Andrey A. Vigasin
Keyword(s):  
Far Infrared ◽  
Gas Mixtures ◽  
Rare Gas ◽  
Induced Absorption

COLLISION-INDUCED ABSORPTION OF COMPRESSED GASES IN THE FAR INFRARED, PART II

1965 ◽  
Vol 43 (5) ◽  
pp. 751-769 ◽  
Author(s):  
D. R. Bosomworth ◽  
H. P. Gush
Keyword(s):  
Infrared Spectra ◽  
Room Temperature ◽  
Broad Band ◽  
Far Infrared ◽  
Gas Mixtures ◽  
Frequency Region ◽  
Rare Gas ◽  
Induced Absorption ◽  
Far Infrared Spectra ◽  
Zero Frequency

The induced spectra of compressed helium–argon and neon–argon mixtures, and of compressed hydrogen, nitrogen, and oxygen have been measured in the frequency region 20 to 400 cm−1. The far-infrared spectra consist of a translational branch and a rotational branch which overlap, except in the rare-gas mixtures where only the translational component exists. The latter is a broad band which extends from zero frequency to about 500 cm−1, with a maximum near 150 cm−1 in the room-temperature gas. In the case of hydrogen the translational branch is readily distinguished from the rotational branch because it lies at a lower frequency than the latter. In the case of oxygen and nitrogen the spacing between the rotational lines is small and the translational and rotational branches overlap completely.

Pressure-induced absorption in nonpolar gases containing tetrahedral molecules

1976 ◽  
Vol 54 (5) ◽  
pp. 611-617 ◽  
Author(s):  
A. D. Buckingham ◽  
A. J. C. Ladd
Keyword(s):  
Dipole Moment ◽  
Field Gradient ◽  
Infrared Radiation ◽  
Far Infrared ◽  
Spectral Moment ◽  
Induced Absorption ◽  
Integrated Intensity ◽  
Tetrahedral Molecules ◽  
Spherical Molecule ◽  
Far Infrared Radiation

The theory of pressure-induced absorption of far infrared radiation by gases is extended to include the contribution of the dipole moment induced in a molecule by the field gradient due to its neighbours. This dipole is nonzero when the molecule lacks a centre of inversion, as in a tetrahedron. In the collision of two tetrahedra, the dipole induced in molecule 2 by the electric field of the octopole moment Ω1 of the partner leads to transitions in which ΔJ(1) = 0, ± 1, ±2, ±3, and ΔJ(2) = 0. The dipole induced by the field gradient of Ω1 leads to ΔJ(1) = 0, ±1, ±2, ±3, and ΔJ(2) = 0, ±1, ±2, ±3, and therefore gives a required increase in absorption at higher frequencies. The field-gradient contribution vanishes in a collision involving a tetrahedral and a spherical molecule. General expressions are given for the field-gradient contributions to the integrated intensity and to the −2 spectral moment.

Collision-induced absorption in ethane–rare gas mixtures

1983 ◽  
Vol 61 (4) ◽  
pp. 633-640 ◽  
Author(s):  
I. R. Dagg ◽  
L. A. A. Read ◽  
A. Anderson
Keyword(s):  
Fourier Transform ◽  
Temperature Dependence ◽  
Quadrupole Moment ◽  
Gas Mixtures ◽  
Rare Gas ◽  
Fourier Transform Spectrometer ◽  
Rare Gases ◽  
Induced Absorption ◽  
Absolute Value ◽  
The Absolute

The collision-induced spectra of mixtures of ethane and each of the rare gases He, Ar, Kr, and Xe in the 40–360 cm−1 region have been obtained using a Michelson Fourier transform spectrometer. In addition, the temperature dependence of the absorption in ethane and ethane–xenon mixtures is reported. All results have been analyzed according to the theory for quadrupole induced rotation–translation absorption. The absolute value of the quadrupole moment of ethane is estimated to be less than 1.0 B and most likely less than 0.5 B. Various speculations are made concerning the induction mechanisms (other than quadrupolar) for each of the mixtures.

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