Absolute frequency determination of molecular transition in the Doppler regime at kHz level of accuracy

Abstract

We measured absolute frequency of the unperturbed P7 P7 O2 B-band transition ν0= 434783.5084857(82) GHz and the collisional self-shift coefficient δ=−9.381(62)×10−21 GHz/(molecule/cm3). With Doppler-limited spectroscopy we achieved the relative standard uncertainty of 2×10−11 on line position, typical for Doppler-free techniques. Shapes of the spectral line were measured with a Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer referenced to an 88Sr optical atomic clock via an optical frequency comb.