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Journal ArticleDOI

Empirical values of the ground state energies for methane transitions between 5500 and 6150 cm −1

Jack S. Margolis
- 20 May 1990 - 
- Vol. 29, Iss: 15, pp 2295-2302
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TLDR
The variation of the measured strengths allows the energy of the lower state of the transition to be determined empirically using the temperature dependence of the methane partition function and the Boltzmann factor for the energy level populations.
Abstract
The strengths of more than 1600 lines of CH(4) have been measured in the spectral interval between 5500 and 6150 cm(-1) at room temperature and reduced temperatures. The variation of the measured strengths allows the energy of the lower state of the transition to be determined empirically using the temperature dependence of the methane partition function and the Boltzmann factor for the energy level populations. An error analysis, based on assumed errors in the strength and temperature measurements, is included. The average measured uncertainty in J is 0.2.

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Citations
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Journal ArticleDOI

The HITRAN 2008 molecular spectroscopic database

TL;DR: The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity, and molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth.
Journal ArticleDOI

The 2009 edition of the GEISA spectroscopic database

N. Jacquinet-Husson, +58 more
TL;DR: The GEISA database as mentioned in this paper is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols.
Journal ArticleDOI

Pressure broadening in the 2ν 3 band of methane and its implication on atmospheric retrievals

TL;DR: In this article, a multispectrum nonlinear constrained least squares approach based on Optimal Estimation was applied to derive the spectroscopic parameters by simultaneously fitting laboratory spectra at different ambient pressures assuming a Voigt line-shape.
References
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Journal ArticleDOI

The ground state of methane 12CH4 through the forbidden lines of the ν3 band

TL;DR: In this article, the ground state energies of the ν3 band of methane, 12CH4, were determined using combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), with uncertainties of about 0.001 cm−1.
Journal ArticleDOI

Measured line positions and strengths of methane between 5500 and 6180 cm(-1).

TL;DR: The positions and strengths of more than 2000 methane absorption lines stronger than 1.0 x 10(-4) cm(-2) atm (-1) have been measured in the 5500-6180-cm(-1) spectral region.
Journal ArticleDOI

On the rotational partition function for tetrahedral molecules

TL;DR: In this article, a rigorous calculation of the quantum-mechanical rotational partition function for tetrahedral XY4 molecules yields Qr = ( 1 12 )(2IY + 1)4π 1 2 α- 3 2 exp(α/4), where IY is the spin of the Y nucleus, and α ≡ Bhc/kT.
Journal ArticleDOI

Strengths and lorentz broadening coefficients for spectral lines in the ν3 and ν2 + ν4 bands of 12CH4 and 13CH4

TL;DR: In this paper, the authors measured spectral lines in the ν3 and ν2 + ν4 bands of 12CH4 and 13CH4 from 2870-2883 cm−1 using a tunable diode laser spectrometer.
Journal ArticleDOI

Self-broadened widths and absolute strengths of 12CH4 lines in the 1310–1370 cm-1 region

TL;DR: In this article, the authors measured the self-broadened widths and absolute strength of 12CH4 lines in the 1310-1370 cm-1 spectral region using Fourier transform absorption spectroscopy with a 0.003 cm 1 resolution.
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