Knowledge Bank

Collision-induced absorption (CIA) of the fundamental band of pure oxygen has been obtained over the temperature range $-80\circ$ to $+85\circ C$. The integrated band intensity is at a minimum at $0\circ C$ and increases on either side of this temperature. Band intensities of the CIA in the fundamental band of $N2$ as well as the $CO2$ Fermi dyad are currently under investigation. Preliminary results indicate that the temperature dependence of the band intensity of the nitrogen CIA parallels that of $O2$. In contrast, the integrated intensities of the $1000/0200$ Fermi dyad in $CO2$ increase steadily as the temperature is decreased. The integrated intensities double as the temperature goes from $+72\circ$ to $-80\circ C$. This indicates that at low temperatures the bound dimer is the major species in the gas. The band structure obtained at elevated temperatures will be presented.