Collision-induced absorption in gaseous sulphur hexafluoride

1991 ◽  
Vol 69 (6) ◽  
pp. 671-678 ◽  
Author(s):  
C. G. Joslin ◽  
C. G. Gray ◽  
I. R. Dagg ◽  
A. Anderson ◽  
T. F. Gmach ◽  
...  
Keyword(s):  
Information Theory ◽  
Absorption Spectrum ◽  
Ftir Spectroscopy ◽  
Line Shape ◽  
Spectral Region ◽  
Reasonable Agreement ◽  
Substantial Contribution ◽  
Sulphur Hexafluoride ◽  
Upper Limit ◽  
Theory And Experiment

The absorption spectrum of gaseous sulphur hexafluoride has been measured in the spectral region from approximately 20 to 140 cm−1 at 339 K. The experiments were performed over a range of densities from 65 to 109.6 amagat (for SF6, 1 amagat = 45.3 mol m−3), using FTIR spectroscopy. From the density dependence of the absorption, the collision-induced spectrum was clearly separated from the strong allowed transitions of vibrational difference bands at 26 and 91 cm−1. Our results for the induced spectrum differ substantially, both in overall magnitude and in shape, from earlier data. We interpret the absorption as due to anisotropic overlap induction; however, a substantial contribution from a hexadecapolar mechanism cannot be ruled out. We can place an upper limit of approximately 7 × 10−42 esu on the hexadecapole moment. The induced line shape is calculated using information theory, based on our knowledge of the zeroth and second moment of the frequency spectrum. Reasonable agreement is found between theory and experiment.

The octopole and hexadecapole moments of N2O from collision-induced absorption measurements

1990 ◽  
Vol 68 (12) ◽  
pp. 1440-1445 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
T. F. Gmach ◽  
C. G. Joslin ◽  
W. Smith
Keyword(s):  
Information Theory ◽  
Stainless Steel ◽  
Absorption Spectrum ◽  
Fourier Transform ◽  
Line Shape ◽  
Theoretical Expression ◽  
Absorption Cell ◽  
Ir Laser ◽  
Fourier Transform Ir ◽  
Absorption Measurements

The absorption spectrum of gaseous N2O was measured in the spectral region from approximately 15–120 cm−1 at 11 different densities from 3.3 to 64.5 amagat. (An amagat is defined as the density of a gas at N.T.P.) The data were obtained with a Michelson Fourier transform IR spectrometer and a far IR laser using a stainless steel absorption cell 9.26 cm in length. From the density dependence of the absorption, the collision-induced spectrum above approximately 60 cm−1 was clearly separated from the relatively strong allowed transitions peaking at the lower frequency near 22 cm−1. From theoretical expressions for the line shape, derived using information theory, and a reliable value of the quadrupole moment (obtained from the birefringent measurements), we estimate the octopole moment to be 7.6 × 10−34 esu and the hexadecapole moment to be 16.9 × 10−42 esu. Alternatively, if the hexadecapolar contribution is considered to be negligible, then we estimate the octopole moment to be 9 × 10−34 esu. These results are consistent with measurements of the total integrated absorption of the IR band assuming a theoretical expression for the contribution due to the allowed dipole transitions.

Unbalance Response of a Dual Rotor System: Theory and Experiment

1993 ◽  
Vol 115 (4) ◽  
pp. 427-435 ◽  
Author(s):  
K. Gupta ◽  
K. D. Gupta ◽  
K. Athre
Keyword(s):  
System Theory ◽  
Transfer Matrix ◽  
Mode Shape ◽  
Reasonable Agreement ◽  
Complex Variables ◽  
Rotor System ◽  
Experimental Results ◽  
Unbalance Response ◽  
Theoretical Results ◽  
Theory And Experiment

A dual rotor rig is developed and is briefly discussed. The rig is capable of simulating dynamically the two spool aeroengine, though it does not physically resemble the actual aeroengine configuration. Critical speeds, mode shape, and unbalance response are determined experimentally. An extended transfer matrix procedure in complex variables is developed for obtaining unbalance response of dual rotor system. Experimental results obtained are compared with theoretical results and are found to be in reasonable agreement.

scholarly journals Is there a trend in cirrus cloud cover due to aircraft traffic?

2005 ◽  
Vol 5 (8) ◽  
pp. 2155-2162 ◽  
Author(s):  
F. Stordal ◽  
G. Myhre ◽  
E. J. G. Stordal ◽  
W. B. Rossow ◽  
D. S. Lee ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Cloud Cover ◽  
Reasonable Agreement ◽  
Global Scale ◽  
Cirrus Cloud ◽  
Positive Trend ◽  
Spatially Correlated ◽  
Upper Limit ◽  
Main Emphasis ◽  
The Mean

Abstract. Trends in cirrus cloud cover have been estimated based on 16 years of data from ISCCP (International Satellite Cloud Climatology Project). The results have been spatially correlated with aircraft density data to determine the changes in cirrus cloud cover due to aircraft traffic. The correlations are only moderate, as many other factors have also contributed to changes in cirrus. Still we regard the results to be indicative of an impact of aircraft on cirrus amount. The main emphasis of our study is on the area covered by the METEOSAT satellite to avoid trends in the ISCCP data resulting from changing satellite viewing geometry. In Europe, which is within the METEOSAT region, we find indications of a trend of about 1-2% cloud cover per decade due to aircraft, in reasonable agreement with previous studies. The positive trend in cirrus in areas of high aircraft traffic contrasts with a general negative trend in cirrus. Extrapolation in time to cover the entire period of aircraft operations and in space to cover the global scale yields a mean estimate of 0.03 Wm-2 (lower limit 0.01, upper limit 0.08 Wm-2) for the radiative forcing due to aircraft induced cirrus. The mean is close to the value given by IPCC (1999) as an upper limit.

scholarly journals Interdependent value auctions with insider information: Theory and experiment

2019 ◽  
Vol 117 ◽  
pp. 218-237 ◽  
Author(s):  
Syngjoo Choi ◽  
José-Alberto Guerra ◽  
Jinwoo Kim
Keyword(s):  
Information Theory ◽  
Insider Information ◽  
Theory And Experiment

The Barrier to Rotation About the N—N Bond in N-Nitrosamines as Determined by Nuclear Magnetic Resonance Total Line Shape Analysis

1974 ◽  
Vol 52 (17) ◽  
pp. 3028-3036 ◽  
Author(s):  
J. D. Cooney ◽  
S. K. Brownstein ◽  
J. W. ApSimon
Keyword(s):  
Shape Analysis ◽  
Line Shape ◽  
Energy Barrier ◽  
Activation Parameters ◽  
Substantial Contribution ◽  
Resonance Structure ◽  
Bond Rotation ◽  
Line Shape Analysis ◽  
Bond Character ◽  
Nitrogen Bond

The energy barrier to internal N—N bond rotation in five cyclic and two bicyclic N-nitrosamines [Formula: see text]has been determined using high temperature 100 MHz n.m.r. spectroscopy. A substantial contribution from the ionic resonance structure of [Formula: see text] produces considerable double bond character in the nitrogen–nitrogen bond and a concomitant increase in the rotational barrier about the N—N bond. The molecules were examined in the[Formula: see text]liquid state and had ring sizes varying from five to nine atoms. The Arrhenius and Eyring activation parameters for the energy barrier were determined using total line shape analysis and the intensity ratio approximation method. The energy barrier to N—N bond rotation was found to range from 23–29 kcal/mol depending on the molecular structure and the solvent.

The absorption spectrum of monodeuterated methane /CH3D/ in the 6000-12000 A spectral region

1977 ◽  
Vol 213 ◽  
pp. L139 ◽  
Author(s):  
R. G. Danehy ◽  
B. L. Lutz ◽  
T. Owen ◽  
T. W. Scattergood ◽  
W. Goetz
Keyword(s):  
Absorption Spectrum ◽  
Spectral Region
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