Atmospheric oxygen microwave spectrum--Experiment versus theory

Abstract

The microwave spectrum of oxygen (O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -MS) was investigated with a pressure-scanning dispersion spectrometer between 53.5 and 63.6 GHz under simulated atmospheric conditions. First, the strength and width parameters of 21 lines ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K^{\pm}= 1</tex> to 25)were determined from low pressure (<20 torr) data with accuracies on the order of 1 to 4 percent and the results extended to other lines ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K^{pm}</tex> = 25 to 35). Then, O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -MS intensities (dispersion and attenuation by oxygen and air) were measured between 100 and 800 torr and compared with Rosenkranz's band shape model. A set of interference coefficients was established to produce good agreement between experiment and theory. Also, at 61 GHz the refractivities of 13 atmospheric gases were checked. The improved calculation scheme of atmospheric molecular EHF ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sim40</tex> to 140 GHz) characteristics is presented as a transfer function incorporating a set of 144 line parameters (36 each of position, strength, width, and interference) with frequency, pressure and temperature dependencies.