Microwave Absorption in Compressed CO2

Abstract

Induced absorption in carbon dioxide has been studied at a frequency of 9260 Mc/sec over the temperature range 270°—500°K and to pressures as high as 95 atm. Since the dielectric loss ε″ is expected on the basis of the dispersion relations to be proportional to frequency throughout the microwave region the data has been fit with an expansion in the amagat density ρ of the form ε′′/ν̄=Aρ2+Bρ3, where ν̄ is in wavenumbers. It is found that A=2.5(1)×10−8(T/273)−3.0(1), and B/A=−1.05(8)×10−2(T/273)−2.3(3). The molecular quadrupole moment calculated from the first coefficient of the dielectric loss A is then 6.7×10−26 (esu).