High accuracy spectroscopic parameters of the 1.27 µm band of O2 measured with comb-referenced, cavity ring-down spectroscopy. (August 2021)

• Record Type: Journal Article
• Authors: Fleurbaey, Hélène; Reed, Zachary D.; Adkins, Erin M.; Long, David A.; Hodges, Joseph T.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 270(2021)
• Publication Date: 2021-08
• Subjects: O2 -- Line intensity -- Line shape parameters -- Collisional induced absorption -- Hartmann-Tran profile -- Cavity ring-down spectroscopy; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2021.107684
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: High-precision, low-uncertainty CRDS measurements of 1.27 µm air-broadened O2 band line with frequency axis linked to Cs clock. New line list reported using Dicke-narrowing constrained Hartmann-Tran profile. Multi-spectrum line shape analysis and Monte Carlo model indicates strong numerical correlation between Dicke narrowing and speed dependent narrowing mechanisms. Intensities and broadening coefficients measured with relative uncertainties of 0.15 % and 0.05 %, respectively and line positions measured with 60 kHz uncertainty. Measurements values of binary absorption coefficients for collision induced absorption spectrum in sub-percent-level agreement with prior work. Abstract: We present broadband spectroscopic parameters in the a 1 Δ g − X 3 Σ g − (0, 0) band of 16 O2 centered near 1.27 µm. High-fidelity absorption spectra were acquired on room-temperature air samples over the pressure range of 3.3 kPa to 100 kPa using a length-stabilized cavity ring-down spectrometer, with spectrum frequencies linked to a Cs clock via an optical frequency comb. Parameters were determined by multi-spectrum fitting of advanced line profiles to the measured spectra. This analysis yielded line intensities, positions, collisional broadening and shifting coefficients, Dicke narrowing and speed dependent line shape parameters, first-order line mixing coefficients, and O2 -air binary absorption coefficients for collision-induced absorption. We report relative standard uncertainties in the line intensities and broadening coefficients of 0.16 % and 0.05 %, respectively, and line position uncertainties of 60 kHz (2 × 10 −6 cm −1 ). Our analysis reveals strong numerical correlation in fits of the Dicke narrowing and speed dependent widths and shows that inclusion of a recently proposed modification to the Hartmann Tran line profile can increase fitted Dicke narrowing frequencies by as much as 50 %.