Line positions, pressure broadening and shift coefficients for the second overtone transitions of carbon monoxide in argon

- Five P branch 3-0 band transitions of carbon monoxide in argon were measured.
- Line positions were determined with accuracy better than 420 kHz.
- Frequencies were linked to primary frequency standard through UTC(AOS) reference.
- First line shift measurements of CO 3-0 band in argon were done.

Absolute positions and spectral line-shape parameters of carbon monoxide 0→3 band, P branch transitions are reported. The speed-dependent effects and the influence of velocity-changing collisions were taken into account in the fitted line-shape models. For the first time the values of pressure shift coefficients of CO in argon for this band were determined. The measurements were made with the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer, with the frequency axis linked through an optical frequency comb to the UTC(AOS) frequency reference based on a hydrogen maser. Achieved uncertainties of line positions are between 70 kHz and 420 kHz.