Predissociation linewidths for the Schumann-Runge bands of 16O18O

We have measured predissociation linewidths for rotational lines from the (2-0)–(15-0) Schumann-Runge bands of ¹⁶O¹⁸O. The behaviour of the vibrational widths is intermidiate between those observed previously for ¹⁶O₂ and ¹⁸O₂, with predissociation maxima at ν' = 4, 7, 10, (15). Our experimental linewidths are found to exhibit systematic variation with rotation for some of the bands studied. A model of the predissociation, including the interactions of the B³Σ^-_u state with repulsive ⁵Π_u, ³Π _u, ¹Π_u and ³Σ⁺_u states, and with molecular interaction parameters determined by a least-squares fit to previous ¹⁶O₂ linewidths, is found to predict accurately the observed vibrational and rotational dependences of linewidths for ¹⁶O¹⁸O.