Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines. (February 2020)

• Record Type: Journal Article
• Authors: Nguyen, H.T.; Ngo, N.H.; Tran, H.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 242(2020)
• Publication Date: 2020-02
• Subjects: Molecular dynamics simulations -- rCMDS -- O2-broadened CO2 -- Line shape -- Line mixing -- Speed-dependent Nelkin–Ghatak profile -- Speed dependence -- Dicke narrowing; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2019.106729
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Calculations of O2-broadened CO2 spectra using requantized molecular dynamics simulations. Spectra were fitted with the speed-dependent Nelkin–Ghatak profile and the first-order line mixing. Line-shape parameters and their temperature dependences were retrieved for CO2/O2 and CO2/air. Comparisons between predictions and experimental data show very good agreement. Abstract: Requantized classical molecular dynamics simulations (rCMDS) were performed for CO2 highly diluted in O2 at 200, 250, 296 and 350 K using a site-site intermolecular potential. The simulations were made for 0.5 atm of O2 pressure and for a large range of Doppler widths, covering near-Doppler regime to collisional-dominant regime. The Fourier-Laplace transform of the auto-correlation functions of the dipole moment, calculated by rCMDS, leads to the associated spectra of CO2 broadened by O2 . Different effects of collisions between CO2 and O2 molecules are included in the simulated spectra. In order to determine the profile parameters of O2 -broadened CO2 lines, the rCMDS-calculated spectra were fitted with the speed-dependent Nelkin–Ghatak profile associated with the first-order line mixing. The collisional line broadening coefficient, its speed dependence component, the Dicke narrowing and the first-order line-mixing parameters were retrieved for lines with J up to 50 and for all considered temperatures. The temperature dependences of these line-shape parameters were then deduced using the usual single power law. From results obtained in this work and those obtained for CO2 in N2 [ Nguyen et al., J Chem Phys, 149, 224301, 2018 ], the air-broadened line-shape parameters and their temperature dependences for CO2 lines were calculated and compared with literature data showing very good agreement.