Abstract
A self-referenced frequency comb has been combined with a cavity ring down (CRD) spectrometer to achieve a sub-MHz accuracy on the derived positions of the absorption lines. The frequency emitted by the distributed feedback (DFB) laser diode used in the spectrometer was obtained from the frequency of its beat note with the closest mode of the frequency comb. This delivers excellent frequency accuracy over a broad spectral region with sensitivity (noise equivalent absorption) of 1×10–11cm−1Hz−1/2.This setup is used to measure the absorption spectrum of CO over a wide range corresponding to the 3–0 band (6172.5–6418.0cm−1). Accurate values of line centers are measured for a total of 184 lines of four CO isotopologues, namely 12C16O, 13C16O, 12C18O and 12C17O present in “natural” abundances in our sample. The measurements include the first extensive study of the 3–0 band of 12C18O and 12C17O, of the 4–1 hot band of 12C16O and the detection of new high-J transitions of the 3–0 band of 12C16O up to J=34. The line centers were corrected for the self-pressure shift and used to derive the upper state spectroscopic parameters. The obtained standard deviation of about 300kHz and 500kHz for the 3–0 band of 12C16O and of the minor isotopologues, respectively, is a good estimate of the average accuracy of the reported line centers. The resulting 3–0 line list of 12C16O provided as Supplementary material includes 69 reference line positions with a 300kHz accuracy for the 6183–6418cm−1 region.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Journal of Quantitative Spectroscopy and Radiative Transfer
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.