Self-broadening of 16O12C16O ν3-band lines

Abstract

Absorption spectra of pure 16O12C16O have been recorded, at room temperature and for five pressures between 0.2 and 1atm, in the very intense ν3 band. As recently done for CO, this was achieved using a high resolution (0.005cm−1) Fourier transform spectrometer together with a specially designed cell. With the latter, set to a path length of about 20μm, the absorption by extremely intense lines is measured under appropriate (non saturating transmission) absorption conditions, regardless of the gas pressure. The recorded spectra have been adjusted one-by-one using Voigt line-shapes in order to retrieve the line positions and the Lorentz widths for the P(40) to R(40) lines. The results show that accurate self-broadening coefficients γ are obtained but that experimental uncertainties forbid any reliable determinations of the pressure-induced shifts δ due to the fact that they are about two order of magnitude smaller than γ. The present values of γ show the limited accuracy of previous determinations for the exact same lines. They are in very good agreement with those in the HITRAN database if the latter, which are for a speed-dependent Voigt profile, are properly corrected to correspond to a Voigt profile.