Isolated line shapes of molecular oxygen: Requantized classical molecular dynamics calculations versus measurements

We present comparisons between measured isolated line shapes of molecular oxygen in air at various pressures and those calculated, free of any adjusted parameter, using requantized classical molecular dynamics simulations (rCMDS). The measurements have been made for the R1Q2, P9P9, P11P11, P13P13, and P15Q14 transitions in the O2 singlet-Δ band [a1Δg←X3Σg-(0,0)] by the frequency-stabilized cavity ring-down spectroscopy technique. This work extends a previous study made for a single oxygen line [Phys. Rev. A 87, 032510 (2013)PLRAAN1050-294710.1103/PhysRevA.87.032510] and confirms the quality of this theoretical approach over broad ranges of pressure and rotational quantum number. Indeed, not only the collisional broadening coefficients but also the (small) deviations of observed line shapes with respect to the Voigt profile are accurately predicted. These results illustrate the viability of using the rCMDS method as a benchmark for the development and testing of simpler parametrized line profiles that are suitable for the analysis of underlying physical mechanisms and for atmospheric remote sensing applications.