Transition frequencies of oxygen B-band lines measured with optical frequency comb assisted cavity ring-down spectroscopy

Abstract

Transition frequencies of weak B-band lines of O2 were measured with low uncertainties. These results were compared to data available in the literature. In order to achieve reported accuracy we took into account in the data analysis several subtle line-shape effects, such as speed dependence of collisional broadening and Dicke narrowing. We found that the speed-dependent Nelkin-Ghatak profile can properly describe experimental line shapes in the investigated pressure range of up to 22 Torr. Our experimental setup consists of the Pound-Drever-Hall locked frequency-stabilized cavity ring-down spectrometer. This spectrometer provides high-resolution and very high signal-to-noise ratio of measured spectra. It was recently linked to the optical frequency comb working in the visible region of spectrum. This upgrade allows for accurate determination of the absolute frequency axis of the CRD spectrum by direct measurement of the probe laser frequency.