Molecular transition frequencies of CO2 near 1.6 µm with kHz-level uncertainties

CRDS measurements of air-broadened lines in the 1.6 µm band of 12CO2: Line shape parameters with their temperature dependence

“…Recently, several CRDS studies have reported highly accurate measurements (at the kHz level or below) of the positions of the studied CO 2 transitions by saturation spectroscopy [6] or from Doppler limited spectra [4,5]. The comparison of our fitted positions with the values provided by these studies shows averaged differences (over the 5 transitions) from 25 kHz at 250K and 285 K, for which the best signal-to-noise ratios are achieved, to 150 kHz in the worst case at 320 K. Fixing the positions to these very accurate values during the multi-spectrum fit procedure modifies only marginally the values retrieved for the different line-shape parameters.…”

“…Due to its importance for remote sensing applications from ground-or satellite-based observatories, the 30013-00001 band of 12 CO 2 in the 1.6 µm atmospheric transparency window has been the subject of many laboratory studies using Fourier transform spectroscopy (FTS) [1,2 and references herein] and cavity ring down spectroscopy (CRDS) [3,4,5,6,7]. This band is especially used to monitor the column averaged CO 2 atmospheric dry air mole fraction, X CO2 , in several satellite missions like the Orbiting Carbon Observatory-2 (OCO-2) [8,9,10], OCO-3 [11] and GOSAT [12].…”

The (2–0) R(0) and R(1) transition frequencies of HD determined to a 10−10 relative accuracy by Doppler spectroscopy at 80 K

“…This level of accuracy (relative uncertainty of 5 Â 10 À13 ) is at the state-of-the-art for molecular transition frequencies. [43][44][45] In the case of the R(1) transition of HD, our accuracy is at the level of the best previous determinations both in saturation regime and in Doppler regime. Note that the only accurate determination in Doppler regime was obtained from room temperature spectra recorded with pressures between 100 and 1500 Pa. 19 The sensitivity of the CRDS set-up used in the present work allowed us to record spectra at a significantly 2).…”

“…This level of accuracy (relative uncertainty of 5 × 10 −13 ) is at the state-of-the-art for molecular transition frequencies. 43–45…”

12CO2 transition frequencies with kHz-accuracy by saturation spectroscopy in the 1.99–2.09 μm region

“…In the former spectral region, numerous line profile studies 2–6 as well as highly accurate frequency measurements 7–14 have been reported so far. In particular, transition frequencies with kHz-accuracy were determined both in the Doppler limited regime 8,9,12,13 and in the saturation regime. 10,14…”