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Abstract: The McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (NSO) on Kitt Peak, Arizona, was used to record infrared high resolution absorption spectra of CO2 spectra broadened by O2. These spectra were analyzed to measure O2-broadened half-width coefficients, O2-induced pressure-shift coefficients and speed dependent parameters for transitions in the 30013←00001 and 30012←00001 bands of 16O12C16O located near 6227 and 6348cm−1, respectively. All spectra were obtained at room temperature using the long path, 6m base path White cell available at NSO. A multispectrum nonlinear least-squares fitting algorithm employing Voigt line shapes modified to include line mixing and speed dependence was used to fit simultaneously a total of 19 spectra in the 6120–6280cm−1 (30013←00001) and 6280–6395cm−1 (30012←00001) spectral regions. 16 of the 19 spectra analyzed in this work were self broadened and three spectra were lean mixtures of CO2 in O2. The volume mixing ratios of CO2 in the three spectra varied between 0.06 and 0.1. Lorentz half-width and pressure-induced shift coefficients were measured for all transitions in the P(50)–R(50) range in both vibrational bands. The results obtained from present analysis have been compared with measurements available in the literature for self-, air-, oxygen- and argon-broadening. No significant differences were observed between the broadening and shift coefficients of the two bands. The N2-broadened half-width and pressure-shift coefficients were computed from measured air- and O2-broadened width and shift coefficients. [ABSTRACT FROM AUTHOR]

Abstract: Lorentz air-broadened half widths, pressure-induced shifts and their temperature dependences have been measured for over 430 transitions (allowed and forbidden) in the ν 4 band of 12CH4 over the temperature range 210–314K. A multispectrum non linear least squares fitting technique was used to simultaneously fit a large number of high-resolution (0.006–0.01cm−1) absorption spectra of pure methane and mixtures of methane diluted with dry air. Line mixing was detected for pairs of A-, E-, and F-species transitions in the P- and R-branch manifolds and quantified using the off-diagonal relaxation matrix elements formalism. The measured parameters are compared to air- and N2-broadened values reported in the literature for the ν 4 and other bands. The dependence of the various spectral line parameters upon the tetrahedral symmetry species and rotational quantum numbers of the transitions is discussed. All data used in the present work were recorded using the McMath–Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak. [Copyright &y& Elsevier]