Measured Transition Probabilities for the Schumann-Runge System of Oxygen

Abstract

Transition probabilities for the Schumann-Runge system of O2 have been measured in absorption in the wavelength region 2650–3900 A. Oxygen was heated in a shock tube to temperatures up to 4500°K, thereby populating high vibrational and rotational levels. Absorption spectra were photographed using a high-speed flash lamp and a large Littrow quartz spectrograph. Transition probabilities for the bands of three sequences, associated with the zero, 1st, and 2nd vibrational levels of the excited electronic state, yield an f value of 0.048±0.008 which, when corrected for wavelength dependence, is about ⅓ that determined in the vacuum ultraviolet. This corresponds to a decrease in transition probability with increasing internuclear separation. Line-width variations with temperature and density have also been measured. The optical diameter for O2–O2 collisions was determined as 6 A and for O2–O collisions as 10 A.