Pressure-broadening in the Schumann-Runge bands of molecular oxygen

The pressure-broadened widths for selected rotational lines from the (2-0) to (15-0) Schumann-Runge bands of O 2 have been measured at pressures up to 60 atm. The self-broadening coefficient exhibits no dependence on rotation and a small dependence on vibration, in agreement with theoretical expectations, and may be taken as 0.20 cm -1/atm FWHM, implying an optical collision diameter of 6.2 Å. The broadened absorption lines are shifted towards longer wavelengths and are asymmetric with a steeper blue wing, both of these effects increasing with pressure.