15min:
MODELING N2 AND H2 BROADENED CH4 INFRARED ABSORPTION SPECTRA. LINE-MIXING MODEL AND COMPARISONS WITH MEASUREMENTS.

HA TRAN AND JEAN-MICHEL HARTMANN, LISA-Faculté des Sciences et Technologie, 94010 Créteil Cedex, France.

Line-mixing effetcs have been studied in nu3 and nu4 bands of CH4 perturbed by N2 and H2 at various temperatures. The absorption in the 1100-1500 and 2800-3200 cm-1 spectral regions for total pressures in the 0.25-2 and 25-500 atm ranges have been measured. A line-mixing model is proposed wich is based on state-to-state collisional transfert rates calculated from intermolecular potential surface with a semiclassical approach. The line-coupling relaxation matrix is constructed from these state-to-state collisional transfert rates and some empirical parameters. The results of comparisons between measurements and spectra computed accounting for and neglecting line-mixing prove the satisfactory quality of the model. Calculations with the line-mixing model of atmospheric spectra are also made.