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Main text We present primary spectroscopic measurements of line intensities in the 3-0 vibrational band of 12 C 16 O. This international measurement campaign was organized under the auspices of the Consultative Committee for Amount of Substance (CCQM) and involved six laboratories carrying out independent measurements of more than forty rotation-vibration transitions. A total of three measurement techniques on samples of pure carbon monoxide were applied in this intercomparison, including Fourier transform spectroscopy, cavity ring-down spectroscopy, and cavity mode dispersion spectroscopy. Using advanced spectroscopic line shape models and thorough characterization of instrument response to analyze the measured spectra, artifact-free measurements of line intensities were obtained by each laboratory. Average intensities were weighted by the inverse of the combined variance determined from rigorous estimates of combined systematic and statistical uncertainties. Results for all lines from five of the laboratories were scattered about the weighted mean value by nominally one part per thousand. Comparison of the weighted integrated band intensity with quantum-chemical calculations differed by nominally one part per ten thousand, thus demonstrating excellent agreement between experiment and theory. These results serve as an experimental benchmark for assessing the uncertainty in theoretical calculations, and they reveal the benefits of coordinated experiments that leverage complementary and independent primary measurements from contributing laboratories. To reach the main text of this paper, click on Final Report . The final report has been peer-reviewed and approved for publication by the CCQM.
Hodges et al. (Wed,) studied this question.