The 0 --> 3 Overtone Band of CO: Precise Linestrengths and Broadening Parameters.

Abstract Linestrengths and self-broadening parameters are determined with a standard uncertainty of 1% for 21 lines in the R branch of the 0 → 3 overtone band of CO around 1.57 μm. The values are lower than those given in the Hitran database by 6–8% for the linestrengths and 1–5% for the collision broadening parameters, and they agree within 0–2% with more recent results obtained with FTIR. Also, results are given for foreign gas broadening by N 2 and H 2 O. The line profiles show clear evidence for collisional narrowing with deviations corresponding to those expected for a Galatry profile. When analyzed in terms of a Voigt profile, this effect causes a reduction in effective Doppler width of about 5%. The linestrengths determined for gas mixtures are used for producing independent values for the CO concentrations. These results are derived without reference to any certified gas standard, and it is suggested that optical spectroscopy satisfies the criteria of a primary method set up by the Consultative Committee for Quantity of Matter (CCQM).