Line-shape analysis for high J R-branch transitions of the oxygen B band

Abstract

High resolution laboratory spectra of several lines from the oxygen B-band R-branch measured with cavity ring-down spectroscopy were fitted with advanced line-shape functions. We show that for the low intensity transitions in the range from 10−26 to 10−28 cm−1/(molecule/cm2) the Voigt profile is inadequate to reproduce measured spectra. Experimental results were fitted with the Voigt, speed-dependent Voigt and speed-dependent Nelkin–Ghatak profiles compatible with the Hartmann–Tran profile. We report the line positions, line intensities and other line-shape parameters with subpercent accuracies. The Dunham fit was performed to obtain spectroscopic parameters for both ground and excited states involved in the B-band transitions, some of the parameters have the uncertainty one order of magnitude lower than reported previously. This resulted in an improvement between experimental line positions and Dunham fit positions up to 20 times for the weakest line.