Broadening and line mixing in the 20 0←01 10, 11 10←00  and 12 20←01 1 Q branches of carbon dioxide: Experimental results and energy-corrected sudden modeling

Abstract

Using both a difference frequency spectrometer and a Fourier transform spectrometer, we have measured transitions in the 12 (2)0<--01 (1)0 band of carbon dioxide at room temperature and pressures up to 19 atm. The low-pressure spectra were analyzed using a variety of standard spectral profiles, all with an asymmetric component to account for weak line mixing. For this band, we have been able to retrieve experimental line strengths and the broadening and weak mixing parameters. In this paper we also compare the suitability of the energy-corrected sudden model to predict mixing in the two previously measured Q branches 20 (0)0<--01 (1)0, the 11 (1)0<--00 (0)0, and the present Q branch of pure CO(2), all at room temperature.

Line shape parameters measurement and computations for self-broadened carbon dioxide transitions in the 30012←00001 and 30013←00001 bands, line mixing, and speed dependence

“…We find the room temperature parameters to be: A = 0.0182 cm À1 /atm, k = 0.7396, b = 0.06, and d c = 6.0 Å , very close to the values reported in Ref. [52].…”

“…The basic rates are expressed through an exponential power law dependence [51][52][53] QðJ where E J is the rotational energy of level J. This type of scaling law is often referred to as the ECS-EP model that depends on the d c , A, k, and b parameters of the ECS-EP model.…”

“…Sudden fitting law is an extension of the infinite-order sudden law (IOS) [49] to the case where molecular collisions are not sudden anymore [49][50][51][52][53][54]. Our study followed the implementation described in Ref.…”

“…Our study followed the implementation described in Ref. [52]. The relaxation matrix elements that connect two transitions…”

Line profile study of transitions in the 30012←00001 and 30013←00001 bands of carbon dioxide perturbed by air

“…The Energy Corrected Sudden fitting law is an extension of the Infinite-Order Sudden law (IOS) [38] for cases where molecular collisions are not 'sudden' anymore [38,[40][41][42][43][44]. Many instances have shown that this is true for molecular collisions and consequently that the isolated lines are not Lorentzian at their wings (yet this deviation does not affect the width of the spectral line).…”