The self-broadened, isolated CO₂spectral line shape investigation

Abstract

The measurements of "isolated" CO 2 line (6231.6 cm-1) absorption spectra in wide pressure range from 2 to 1000 mbar were performed on 3-channel high-resolution diode laser spectrometer. 4 theoretical models used for the description of lineshape contour: usual Voigt, Hard-collisional (Rautian), Soft-collisional (Galatry), and Speed-dependent Voigt (Boone). LabView based software used for the testing of current lineshape models. This software performed the nonlinear least-squares fit of the model spectrum to the experimental spectra recorded at each pressure individually. The detailed research of weak lines influence to the retrieved parameters of "isolated" CO2 (6231.6 cm-1, R4 band 30013-00001) is provided. It is shown that the use of Rautian and Galatry lineshape models leads to a significant deviation from linear of the narrowing coefficient pressure dependence while coming to the high pressures range. Most appropriate for the common description of whole experimental spectra in entire range of pressures (up to 1000 mbar) is the SpeedDependent (Boone) profile