In:
Canadian Journal of Physics, Canadian Science Publishing, Vol. 87, No. 5 ( 2009-05), p. 517-535
Kurzfassung:
In this study, 39 high-resolution spectra of pure and air-broadened CO 2 recorded at temperatures between 215 and 294 K were analyzed using a multispectrum nonlinear least-squares technique to determine temperature dependences of air-broadened Lorentz half-width and air-induced pressure shift coefficients for over 100 individual 12 C 16 O 2 transitions in the 30012←00001 (at 6348 cm –1 ) and 30013←00001 (at 6228 cm –1 ) bands. Data were recorded with two different Fourier transform spectrometers (Kitt Peak FTS at the National Solar Observatory in Arizona and the Bomem FTS at NRC, Ottawa), with absorption path lengths ranging between 25 and 121 m. The sample pressures varied between 11 torr (pure CO 2 ) and 924 torr (CO 2 -air) with volume mixing ratios of CO 2 in air between ∼1.5% and 11% (1 torr = 133.322 4 Pa). To minimize systematic errors and increase the accuracy of the retrieved parameters, a constrained multispectrum nonlinear least-squares fitting technique was used to include theoretical quantum mechanical expressions for the rovibrational energies and intensity parameters rather than retrieving the individual positions and intensities line by line. The results suggest no detectable vibrational dependence for the temperature dependences for the air-broadened Lorentz half-width coefficients and the air-induced pressure shift coefficients. The half-width coefficients and temperature dependence exponents were modeled using semiclassical calculations based upon the Robert–Bonamy formalism. A good agreement is seen between the measurements and theoretical calculations. Beyond |m| = 26, a simple scaling factor (0.96) has been applied to the calculated half-width coefficients to match the experimental measurements.
Materialart:
Online-Ressource
ISSN:
0008-4204
,
1208-6045
Sprache:
Englisch
Verlag:
Canadian Science Publishing
Publikationsdatum:
2009
ZDB Id:
2021497-2