O_2 A-band line parameters to support atmospheric remote sensing

Abstract

Numerous satellite and ground-based remote sensing measurements rely on the ability to calculate O_2 A-band [b^1Σ_g^+←X^3Σ_g^−(0,0)] spectra from line parameters, with combined relative uncertainties below 0.5% required for the most demanding applications. In this work, we combine new ^(16)O_2 A-band R-branch measurements with our previous P-branch observations, both of which are based upon frequency-stabilized cavity ring-down spectroscopy. The combined set of data spans angular momentum quantum number, J′ up to 46. For these measurements, we quantify a J-dependent quadratic deviation from a standard model of the rotational distribution of the line intensities. We provide calculated transition wave numbers, and intensities for J′ up to 60. The calculated line intensities are derived from a weighted fit of the generalized model to an ensemble of data and agree with our measured values to within 0.1% on average, with a relative standard deviation of ≈0.3%. We identify an error in the calculated frequency dependence of the O_2 A-band line intensities in existing spectroscopic databases. Other reported lineshape parameters include a revised set of ground-state energies, self- and air-pressure-broadening coefficients and self- and air-Dicke-narrowing coefficients. We also report a band-integrated intensity at 296 K of 2.231(7)×10^(−22) cm molec^(−1) and Einstein-A coefficient of 0.0869(3) s^(−1).

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