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.

Collision-induced absorption in a gaseous mixture of nitrogen and argon

1986 ◽  
Vol 64 (1) ◽  
pp. 7-15 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Laser System ◽  
Gaseous Mixture ◽  
Far Infrared ◽  
Theoretical Development ◽  
Induced Absorption ◽  
Theoretical Line ◽  
Microwave Techniques ◽  
Rotation Spectrum ◽  
System Operating ◽  
Good Agreement

The collision-induced absorption spectrum of a nitrogen–argon gas mixture is treated theoretically and the theory is applied to results obtained by us in the spectral region below 360 cm−1 at four temperatures, namely, 126, 149, 179, and 212 K. The measurements have involved the use of Fourier transform infrared and microwave techniques as well as a far-infrared laser system operating at 84.2 and 15.1 cm−1. The theoretical line shape is obtained from a convolution of a free rotation spectrum and a translational component. The spectra calculated from either information theory alone or combined with Mori theory both show good agreement with experimental results, especially above 30 cm−1. An important feature of the theoretical development is that no adjustable parameters need to be introduced.

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.

Collision–induced absorption in gaseous methane at low temperatures

1986 ◽  
Vol 64 (7) ◽  
pp. 763-767 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Low Frequency ◽  
Frequency Region ◽  
Experimental Results ◽  
Published Data ◽  
Frequency Range ◽  
Simple Method ◽  
Induced Absorption ◽  
Good Agreement

A recently developed theory for collision-induced absorption in methane is compared with experimental results over a wider spectral range and at lower temperatures than previously reported. The present experimental results covering the frequency range below 400 cm−1 exhibit good agreement with other recently published data. The theory shows excellent agreement with experiment in the low-frequency region below approximately 200 cm−1 but underestimates the experimental data somewhat at higher frequencies. Possible theoretical reasons for this discrepancy are given. The theory represents a simple method of obtaining a good estimate of the collision-induced absorption spectra of methane in this frequency region and for extrapolating to lower temperatures for which experimentation is not feasible. In addition, the moments α1 and γ1are compared with earlier determinations and indicate good agreement with the previously obtained values for the octupole and hexadecapole moments of methane.

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.

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.

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.

First experimental observation of far-infrared translational absorption in He–Ne mixtures

1986 ◽  
Vol 64 (7) ◽  
pp. 822-825 ◽  
Author(s):  
Ph. Marteau ◽  
J. Obriot ◽  
F. Fondere
Keyword(s):  
Experimental Observation ◽  
Total Pressure ◽  
Far Infrared ◽  
Absorption Profile ◽  
Spectral Moments ◽  
Induced Absorption ◽  
First Time ◽  
Good Agreement

Collision-induced absorption in He–Ne mixtures has been observed for the first time, in a path of 1.25 m at a total pressure of 1500 bar and a temperature of 77 K. The measured zeroth and second spectral moments are in good agreement with the calculated ones. Some details of the absorption profile are also discussed.

Collision-induced absorption in ethane in the microwave and far-infrared regions

1982 ◽  
Vol 60 (1) ◽  
pp. 16-25 ◽  
Author(s):  
I. R. Dagg ◽  
W. Smith ◽  
L. A. A. Read
Keyword(s):  
Absorption Spectrum ◽  
Far Infrared ◽  
Fourier Transform Spectrometer ◽  
Density Range ◽  
Fir Laser ◽  
Quadrupolar Interaction ◽  
Induced Absorption ◽  
Upper Limit ◽  
Experimental Values ◽  
Microwave Techniques

The collision-induced absorption spectrum of gaseous ethane has been measured at 295 K over a density range from 12 to 45 amagat in the 50–360 cm−1 region and at densities up to 59 amagat at 4.6, 17.4, and 29.6 cm−1. The measurements were made using a Fourier transform spectrometer, an HCN laser, a FIR laser, and microwave techniques. A collision-induced torsional absorption is observed which is centred at 280 cm−1 and is superimposed on the collision-induced rotation–translation absorption. Theoretically, the latter absorption can be ascribed to quadrupolar interaction. This theory has been used to extract estimates for the quadrupole moment of ethane. The results provide an upper limit for the value of Q = −1.28 × 10−26 esu. Lower estimates are also given which reflect a larger contribution to the absorption from the torsional band by using the known absorption profiles for N2 and C2H4. These estimates are compared with other theoretical and experimental values.

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