Predissociation linewidths for the Schumann-Runge bands of 18O 2

Abstract

Predissociation linewidths were measured for rotational lines from the (2-0)–(19-0) Schumann-Runge bands of 18O 2. While the qualitative behaviour of the vibrational linewidths is similar to that observed for 16O 2, with four maxima at various vibrations, for a given band the linewidth may vary significantly between isotopes. As in the case of 16O 2, the experimental linewidths are found to exhibit systematic variation with rotation for most of the bands studied. A model of the predissociation, including the interactions of the B 3Σ - u state with repulsive 5Σ u , 3Π u , 1Π u and 3Π + u states, and with molecular interaction parameters determined by a least-squares fit to experimental 16O 2 linewidths, is found to predict accurately the observed vibrational and rotational dependences of linewidth for 18O 2.