Self-broadening and -shifting of very intense lines of the 1←0 band of ¹²C¹⁶O

Absorption spectra of pure ¹²C¹⁶O have been recorded, at room temperature and for various pressures, in the very intense 1←0 band. This was made using a high-resolution (0.005cm^-1) Fourier transform spectrometer together with a specially designed cell that enables one to adapt the optical path from a few μm up to several mm. Thanks to the latter, absorption by extremely intense lines is measured for the first time under adapted (non saturating transmission) absorbance conditions, even for a pure gas pressure near 1atm. The recorded spectra, obtained for a path length of about 130μm, have been adjusted using Voigt line-shapes in order to retrieve the unperturbed line positions, and the self-broadening and -shifting parameters induced by pressure for the P(20) to R(19) lines. Our results for the line widths confirm the expected very small and undetected influence of vibration on the broadening and demonstrate the inaccuracy of previous high-resolution measurements made under extremely strong absorption conditions. Similarly, our study provides the first accurate self-induced line shifts for the 1←0 band.