Far-Infrared Collision-Induced Absorption in CO2. I. Temperature Dependence

Abstract

Accurate measurements of collision-induced absorption in CO2 are made at a number of temperatures in the range from − 40 to 60°C in the wavelength region 7–250 cm−1. Direct evidence for the separation of the pure translational band from the rotational–translational band is obtained at all temperatures. This and other aspects of the band shape are discussed. Over the entire temperature range, the experimentally determined Kramers–Kronig integral is found to be in good agreement with the theoretical value, i.e., the static dielectric constant. This agreement is achieved only when the contribution of the quadrupole–quadrupole energy in the radial distribution function, of particular importance for CO2 because of its large quadrupole moment, is calculated accurately. A value of the quadrupole moment is obtained, (4.5 ± 0.2)10−26 esu, which is in satisfactory agreement with that obtained by the method of Buckingham and Disch, which does not depend on a knowledge of intermolecular force constants. Induction due to higher multipole moments and the overlap interaction is considered.

The water vapour self- and water–nitrogen continuum absorption in the 1000 and 2500 cm −1 atmospheric windows

“…This is illustrated in figure 5, which shows the continuum profiles (plotted on the linear Y -scale) together with the CIA/dimer spectra of carbon dioxide (except for the allowed n 2 fundamental band) [29,30] and the CIA spectra of nitrogen [31,32]. We assume that the compared spectra have the same physical origin.…”

“…For a dipolar molecule, such as H 2 O, those processes may lead to enforced acts of absorption and/or emission. N 2 roto-translational band [29] collision-induced and dimer absorption profiles in the v 1 , 2v 2 region [28] nitrogen CIA profile in the vibrational fundamental band region [30] 230 K 270 K 346 K CIA bands of dipole-less molecules are well known and quite well studied experimentally (see Frommhold [28]). The fact that molecular collisions produce absorption in regions of forbidden transitions is very important.…”

Effects of high CO2 levels on surface temperature and atmospheric oxidation state of the early Earth

“…The absorption from these bands has been parameterized by the method used by Pollack et al (1980) based on measurements reported by Ho et al (1971), Moore (1971), andG. Birnbaum (private communication, 1979).…”

Investigation of the CH3CN-CO2 Potential Energy Surface (PES) Using Symmetry-Adapted Perturbation Theory (SAPT)

“…The electric dipole moment of CH 3 CN is predicted to be 3.95 debye, while experimenting gives 3.92 debye [41 ]. Values for the C0 2 experimental quadrupole moment [42][43][44][45] vary between -1.34 and 1.5 x 10~1 9 coulomb Ä 2 , while the calculated value lies at the upper end of this range with a value of -1.514 x 10" 19 coulomb Ä 2 . Table 3 compares the S APT components computed using the MC+BS described in section 3 with the equivalent DCBS at the two geometries Gl and G4.…”