Pressure induced shifts of CO2 lines: Measurements in the 003–000 band and theoretical analysis

Abstract

Self-broadened and N2, Ar, He-broadened halfwidth and pressure shift coefficients of the rotational transitions in the 0003–0000 band of 12C16O2 have been measured from laboratory absorption recorded at room temperature with a Fourier transform spectrometer. Comparison is made with the results of a theoretical calculation based on a semiclassical model. Good agreement is obtained for all the IR vibrational bands for which data are available. It has been shown that the shifts mainly originate from vibrational dephasing. Infrared line shifts have been compared with results obtained from stimulated Raman spectroscopy and we show that they are not consistent. A number of possible explanations have been discussed to account for this discrepancy.

Near infrared spectroscopy of carbon dioxide I. 16O12C16O line positions

“…This mandated the use of low gas pressures since previous studies [48][49][50][51][52][53][54][55] showed that CO 2 transitions in the NIR experience large, negative pressure-induced frequency shifts with strong dependencies on J and DJ . Ideally, line positions should be acquired from spectra with pressures of 2 Torr or less.…”

Line shift and mixing in the ν4 and 2ν2 band of NH3 perturbed by H2 and Ar

“…where • S iso 1 is a vibrational phase shift defined from the difference of the isotropic part of the potential in the initial and final states of transition [24]: S iso 1 ¼ S 1;f2 À S 1;i2 ; • the real part of S aniso 2 derived from the anisotropic part of the potential is expressed as the second-order terms of the development of…”

Collisional line broadening in the atmosphere of light particles: problems and solutions in the framework of semiclassical treatment

“…at 300 K. The linewidths are plotted as a function of the rotational quantum number m modulus (m D J for P-branch and m D J C 1 for R-branch) in order to permit a comparison with experimental data 21,22 mainly obtained for P-branches.…”