Comparisons of Measured and Requantized Classical Molecular Dynamics Calculated Line Shape of Air-Broadened Isolated Transitions of Molecular Oxygen

The long-term goal of this study is to propose a readily calculable line profile for molecular oxygen. To this end, the present study discussed calculations of isolated air-broadened oxygen lines and the comparison with high-precision absorption spectra acquired on the near-infrared ¹∆ band of O₂ using the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique¹. Line shapes were calculated based on requantized classical molecular dynamics simulations (rCMDS) for air (20% O₂ + 80% N₂). The comparison of calculated and measured pressure-broadened spectra (through fits using Voigt profiles) demonstrates that the rCMDS can be used to predict subtle but often-observed departures from the Voigt profile. These results illustrate the viability of using the rCMDS method as a benchmark for the development and testing of simpler parameterized line profiles that are suitable for the analysis of underlying physical mechanisms and for atmospheric remote-sensing applications.