Infrared spectroscopy of CO2 isotopologues from 2200 to 7000 cm−1: I-Characterizing experimental uncertainties of positions and intensities

Fourier transform spectra of carbon dioxide enriched in 17O and 18O have been recorded in LADIR (Paris, France) with the Bruker IFS 125-HR between 2000 and 9000 cm−1 at an unapodized resolution of 0.0056 cm−1. In this contribution we present a total of 1861 line positions and intensities retrieved for 46 bands of 12CO2 isotopologues between 2000 and 7000 cm−1 including the 16O12C16O, 17O12C17O, 18O12C18O, 16O12C18O, 16O12C17O, and 17O12C18O species. The objective of this first part of work was to examine the absolute concentrations of various CO2 isotopologues in the sample by comparing our measurements of the line intensities to those available in literature and in HITRAN 2008. The accuracy of the determined abundances of the various isotopologues in our sample could be estimated to be about 2-7% for all above listed isotopologues except for 17O12C17O for which the accuracy on abundance is estimated to be around 20%. The accuracy of the line positions retrieval is better than 0.1×10−3 cm−1. We estimate the relative uncertainty of the line intensities retrieval to be around 1-2% (except for very weak lines), whereas the absolute accuracy to be around 3-15% depending mainly on the accuracy of the determination of the partial pressures for the various isotopologues in our sample, but also on the line strengths and on the spectral region. The estimation of the partial pressures of the various CO2 isotopologues is crucial for retrieving absolute values of line intensities, but this is not an easy task because there are no absolute calibration standards for CO2 intensities. Among the results obtained in this work, measurements are obtained for the first time for the 10011-00001 band of 17O12C17O, 16O12C17O, 16O12C18O, and 18O12C18O species, for the 00011-00001 band of 17O12C18O, and for the 2001i-00001 (i=1, 2, and 3) bands of the 16O12C17O isotopologue.

► FT spectra of CO2 enriched in 17O and 18O recorded between 2000 and 9000 cm−1. ► Line positions and intensities retrieved for 46 bands of all 12CO2 isotopologues. ► Comparisons with literature to estimate the isotopologues pressures in our sample.