Intensity and bandshapes of collision-induced absorption by CO2 in the region of the Fermi doublet

The carbon dioxide dimer spectroscopic patterns are retrieved from the anal ysis of collision-induced absorption (CIA) spectral bandshape at room tempe rature. It is shown that the use of the simplified model based on the symme tric-top approximation allows roughly consistent simulation of the observed (CO2)(2) dimer spectrum. The rotational constants obtained can be consider ed as effective thermally averaged constants which characterize dimeric str ucture, strongly distorted from the ground state. The overall CIA bandshape and the integrated intensity of absorption are broken down into partial co ntributions from tightly bound and metastable dimers and free-pair states. This approach is shown to be in agreement with a wide range of independent spectroscopic and thermodynamic data. (C) 2000 Academic Press.