Theoretical Study of Collision-Induced Double Transitions in CO2-X2 (X2 = H2, N2, and O2) Pairs

Abstract

The double vibrational collision-induced absorptions CO2 (ν3 = 1) + X2 (ν1 = 1) ← CO2 (ν3 = 0) + X2 (ν1 = 0), for X2 = H2, N2, and O2 are studied on the basis of quantum lineshapes computed using isotropic potentials and dipole-induced dipole functions. The linestrengths and energies of the vibration–rotation transitions are treated explicitly for X2 and utilizing the HITRAN database for CO2. From the frequency-dependent absorption profiles, the integrated absorption intensities are determined to be 7.2 ± 1.2, 1.2 ± 0.1, and 1.1 ± 0.2 (10−4 cm−2 amagat−2) for the H2, N2, and O2 collision partners, respectively. The integrated intensities for H2 and N2 agree well with previously measured and calculated results, while the value for O2, which represents the first theoretical determination for this absorption, is approximately four times greater than the only experimental measurement (0.29 × 10−4 cm−2 amagat−2).