Collision-Induced Absorption by CO2 in the Region of nu1, 2nu2

Collision-induced absorption (CIA) by CO2 is measured in the 1100-1600 cm-1 range using a Fourier-transform spectrometer with a resolution of 0.5 cm-1. The current measurements, which agree well with previous ones but are more precise, reveal pronounced structures on top of both unresolved Fermi doublet bands consisting of P-, Q-, and R-like branches. Assignment of Q-branches at 1284.75 cm-1 and 1387.75 cm-1 to (CO2)2 dimers seems highly probable. The nature of other peaks observed in CIA and Raman spectra of the CO2 Fermi doublet region is discussed. Copyright 1999 Academic Press.