Journal ArticleDOI
Absorption of Millimeter to Submillimeter Waves by Atmospheric Water Molecules
TLDR
In this article, the rotational energy levels with normalized Boltzmann factors larger than 5×10−8 at 300°K were calculated, and probabilities of all possible electric dipole transitions among these states, 2277 lines, were calculated using the eigenfunctions thus obtained, and the permanent dipole moment of 1.8546 Debye.Abstract:
Using the values of the rotational molecular parameters (including cencrifugal distortion terms) of the H216O molecule, which can explain 12 observed transitions below 800 GHz, all rotational energy levels with normalized Boltzmann factors larger than 5×10−8 at 300°K are calculated. Probabilities of all possible electric dipole transitions among these states, 2277 lines, are calculated using the eigenfunctions thus obtained, and the permanent electric dipole moment of 1.8546 Debye. Assuming the single and full Lorentzian line forms, we calculated the absorption coefficient for millimeter to submillimeter region. Our result, using the single term Lorentzian line form, agrees quite well with experiment for 1 Torr of water vapor in 760 Torr air at 300°K.read more
Citations
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Journal ArticleDOI
An updated model for millimeter wave propagation in moist air
TL;DR: In this article, a practical atmospheric millimeter-wave propagation model (MPM) is proposed to predict attenuation for dry air at 2.5-430 GHz. But the model is limited to frequencies below 300 GHz and the number of spectroscopic parameters can be reduced to less than 200.
Journal ArticleDOI
Atmospheric EHF window transparencies near 35, 90, 140 and 220 GHz
TL;DR: In this article, the authors made an assessment of the quantitative picture (i.e., models versus experiments and theory), upon which estimations for general radio path behavior can be based.
Proceedings ArticleDOI
The atmospheric water vapor continuum below 300 GHz
TL;DR: In this paper, absolute attenuation rates due to water vapor and moist nitrogen have been measured in the laboratory at 138 GHz, 282 and 300 K, pressures up to 1.5 atm, and relative humidities from 80 to 100 percent.
Journal ArticleDOI
The atmospheric water vapor continuum below 300 GHz
TL;DR: In this paper, absolute attenuation rates due to water vapor and moist nitrogen have been measured in the laboratory at 138 GHz, 282 and 300 K, pressures up to 1.5 atm, and relative humidities from 80 to 100 percent.
Journal ArticleDOI
The pure rotational spectrum of water vapor—A millimeter, submillimeter, and far infrared analysis
TL;DR: In this article, line positions, strengths, and absolute energies for the pure rotational spectrum of water in the region between 0 cm−1 and 877 cm− 1 were calculated in the context of a reduced centrifugal distortion Hamiltonian.
References
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Journal ArticleDOI
The asymmetric rotor : II. calculation of dipole intensities and line classification
Abstract: A table of line strengths for rigid asymmetric rotors is given, by means of which to this approximation the relative intensities of all important rotational lines up to J < 13 for all bands of any molecule can be readily calculated, provided the asymmetry is roughly the same in the initial and final states. A classification of the irregularly spaced lines of the asymmetric rotor is made into ``sub‐branches'' defined by the changes of the K values of the initial level in the limiting prolate and oblate symmetric rotors, and into ``wings'' which collect together lines of the sub‐branches which have uniformly varying strength and Boltzmann factor, and fairly uniform spacing.
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On the Asymmetrical Top in Quantum Mechanics
TL;DR: In this article, a more complete analysis of Witmer's work on the asymmetrical top treated as a perturbation of the symmetrical one is presented, where it is shown that one can deduce the rigorous solution of the problem from those of the algebraic equations of degree $2j+1$ or less.
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Modeling attenuation and phase of radio waves in air at frequencies below 1000 GHz
TL;DR: In this article, an adequate spectroscopic data base for air consists of three terms: (1) resonance information for 29 H2O lines up to 1097 GHz and 44 O2 line up to 834 GHz in the form of intensity coefficients and center frequency for each line; (2) an empirical water vapor continuum spectrum; and (3) a liquid water attenuation term for haze and cloud conditions.
Journal ArticleDOI
Submillimeter Microwave Spectrum ofH2O16
Journal ArticleDOI
Update of the AFGL atmospheric absorption line parameters compilation.
TL;DR: This new version supersedes the last revision of September 1976 and makes major modifications to water vapor, carbon dioxide, methane, and oxygen (identified as molecules 1, 2, 6, and 7 on the compilation).