Collision induced absorption spectra of N2 and CH4

Collision-induced absorption (CIA) spectra of nitrogen and methane are needed to model radiative transfer in atmospheres of objects such as Saturn's moon, Titan. We present rare, extremely low temperature Fourier transform infrared spectra of nitrogen and methane rototranslation CIA in the range of 40–600 cm⁻¹. The peak CIA of methane was found to be 2.05×10⁻⁵ cm⁻¹/amagat² at 123.8 K while nitrogen had a peak value of 1.65×10⁻⁵ cm⁻¹/amagat² at an average temperature of 102.5 K. These measurements were made possible by the unique instrumentation available at the Far-IR beamline at the Canadian Light Source.