Collision-induced Absorption Spectra of N2 and CH4

Abstract Collision-induced spectra are essential for radiative transfer modeling of Titan's atmosphere. We present experimental spectra of nitrogen–methane mixtures with an accompanying fit of N 2 -CH 4 collision-induced absorption in the 30–400 cm −1 region at about 130 K. We found a peak absorption of 2.30 × 10 −5 cm −1 amagat −2 at 75 cm −1 and a secondary peak of 1.35 × 10 −5 cm −1 amagat −2 at 206.5 cm −1 , which agrees with previous studies. Our work does not support the suggestion that N 2 -CH 4 CIA in the far-infrared should be increased by about 50%, as suggested by spectroscopic modeling of Titan using data from A. Borysow & C. Tang.