H2O line positions in the 784-795 nm region with 10−9 accuracy

H216O lines in the spectral range of 12,573-12,753 cm−1 have been recorded by cavity ring-down spectroscopy. Low-pressure water vapor (0.25 Torr) was used to limit the pressure-induced line shift. The absolute line positions were calibrated with Rb atomic transitions and a thermo-stabilized Fabry-Pérot interferometer. Positions of 73 lines with intensities larger than 1×10−25cm−1/(moleculecms−2) have been determined. For well-isolated lines, the absolute frequency accuracy is estimated to be 3×10−5cm−1, which is also confirmed by the ground-state combination differences. Comparison between the line positions obtained in this work and those from HITRAN shows a systematic deviation of 0.001cm−1.

► Cavity ring-down spectra of H2O lines in the 784-795 nm region were measured. ► Absolute positions of 73 water lines were determined with 3E−5 cm−1 accuracy. ► HITRAN H2O line positions in this region have a systematic shift of 0.001 cm−1.