Collisional narrowing of gas phase infrared bands of CO2 at high density

Collisional narrowing due to line-mixing effects are studied in the v3 and 3v3 bands of CO2 perturbed by He and Ar at elevated pressure. The results of computations using an energy-corrected sudden approach are compared with measurements. The model enables the correct prediction of the decrease in the measured band widthwith increasing density which is due to interbranch (R ↔ P) coupling and which is analyzed theoretically in the infrared.