Pressure and temperature dependences of absorption in the v₅ ^RQ₀ branch of CH₃Cl in N₂: Measurements and modeling

The semiempirical approach developed in a previous paper is applied to the v₅ ^RQ₀ branch of CH₃Cl perturbed by N₂. New experiments have been performed using a Fourier transform spectrometer with a resolution of 0.016 cm^-1. Absorption has been measured for total pressures and temperatures in the ranges 0.3-1.1 atm and 197-298 K, respectively. It is shown that our model enables satisfactory prediction of pressure and temperature, as well as wavenumber dependences of absorption, with 11 effective parameters which have been deduced from measured spectra. Analysis shows that the influence of line mixing on the absorption shape is important down to total pressures of about 30 mbar and should thus be accounted for in the treatment of atmospheric spectra.