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 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.

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.

The β+ Decay of 234Np and Other Isospin-Forbidden 0+→ 0+ Fermi Transitions

1984 ◽  
Vol 39 (12) ◽  
pp. 1168-1171
Author(s):  
C. T. Yap ◽  
E. L. Saw
Keyword(s):  
Nuclear Matrix ◽  
Coulomb Potential ◽  
Deformation Parameter ◽  
Theoretical Calculations ◽  
Wave Functions ◽  
Matrix Elements ◽  
Β Decay ◽  
A Value ◽  
Experimental Values ◽  
Good Agreement

Although experimental values of the Fermi nuclear matrix elements vary widely from about 1 × 10-3 to 40 × 10-3 for isospin-forbidden 0+→0+ β transitions, theoretical calculations using the Coulomb potential and Nilsson wave functions yielded values of MF in reasonably good agreement, except that of 234Np. However, our calculation of MF for this decay as a function of the deformation parameter β yielded a value of MF in good agreement with experiment for values of β between 0.1 and 0.2.

The quadrupole moment of acetylene from collision-induced absorption in a gaseous mixture with argon

1988 ◽  
Vol 66 (5) ◽  
pp. 453-459 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
W. Smith ◽  
M. Missio ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Quadrupole Moment ◽  
Line Shape ◽  
Theoretical Estimate ◽  
Gaseous Mixture ◽  
Experimental Spectrum ◽  
Laser Source ◽  
Shape Theory ◽  
Frequency Range ◽  
A Value ◽  
Theoretical Line

The collision-induced spectrum of a mixture of argon and acetylene (100:1) is reported in the frequency range below 240 cm−1. The spectrum is obtained from the total absorption in the mixture at pressures up to 1400 psi (1 psi = 6.89 kPa) and subtraction of the contribution from an allowed difference band of pure acetylene centred near 113 cm−1. The measurements are made with a Michelson Fourier-transform interferometer and with a laser source at 84.1 cm−1. The quadrupole moment of acetylene determined from the experimental spectrum and existing theory for the integrated absorption coefficient is 5.42 (± 0.41) B if a theoretical estimate of the hexadecapole moment is used. Alternatively, a value of 6.14 (± 0.46) B is obtained if the contribution from the hexadecapole moment is assumed to be zero. An extension of the line-shape theory, 1T6, that includes the contribution from hexadecapolar induction is also reported. The resulting theoretical line shape is compared with the experimental spectrum.

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.

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.

Far infrared absorption in gaseous CCl4 and CS2

1989 ◽  
Vol 67 (5) ◽  
pp. 507-514 ◽  
Author(s):  
I. R. Dagg ◽  
M. Missio ◽  
A. Anderson ◽  
W. Smith ◽  
L. A. A. Read
Keyword(s):  
Quadrupole Moment ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Theoretical Estimate ◽  
Gaseous Mixture ◽  
Far Infrared ◽  
Frequency Region

The absorption spectra of gaseous CS2, CCl4, and a gaseous mixture of CCl4 and argon at temperatures up to 400 K in the frequency region below 140 cm−1 are reported. From the results on CCl4, the octupole moment is estimated to be 16 ± 3.0 × 10−34 esu; the hexadecapole moment, 64 ± 12 × 10−42 esu. For CS2, if a previously measured value of 3.6 B for the quadrupole moment is assumed, the hexadecapole moment is estimated to be less that 24 × 10−42 esu, considerably less than an earlier theoretical estimate.

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 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.

On the nitrogen-induced far-infrared absorption spectra

1987 ◽  
Vol 65 (1) ◽  
pp. 90-93 ◽  
Author(s):  
P. Dore ◽  
A. Filabozzi
Keyword(s):  
Experimental Data ◽  
Absorption Spectrum ◽  
Shape Analysis ◽  
Infrared Absorption ◽  
Simple Procedure ◽  
Gaseous Mixture ◽  
Far Infrared ◽  
Line Shape Analysis ◽  
Infrared Absorption Spectra ◽  
Good Agreement

The rototranslational absorption spectrum of gaseous N2 is analyzed, considering quadrupolar and hexadecapolar induction mechanisms. The available experimental data are accounted for by using a line-shape analysis in which empirical profiles describe the single-line translational profiles. We thus derive the simple procedure that allows one to predict the N2 spectrum at any temperature. On the basis of the results obtained for the pure gas, we also propose a procedure to compute the far-infrared spectrum of the N2–Ar gaseous mixture. The good agreement between computed and experimental N2–Ar data indicates that it is possible to predict the far-infrared absorption induced by N2 on the isotropic polarizability of any interacting partner.

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