Insight from correlated fine structure branching ratios

We have studied the v0-dependent predissociation dynamics of the ClO A P3/2 state using velocity-map ion-imaging. Experimental final correlated state branching ratios, i.e. Cl(PJ=3/2,1/2) þ O(PJ=2,1,0) channels, have been measured for v0 = 6–11. We find that the branching ratios are highly variable and depend strongly on v0, providing a window into the v0-dependent predissociation mechanism. A comparison of the experimental results with the recent model of Lane et al. (I. C. Lane, W. H. Howie and A. J. Orr–Ewing, Phys. Chem. Chem. Phys., 1999, 1, 3087) in both the diabatic and adiabatic limits suggests that the dynamics are closer to the diabatic limit. The overall Cl(PJ) branching ratios are in good agreement with the diabatic model results. There are significant differences, however, between theory and experiment at the correlated state level, demonstrating the sensitivity of correlated measurements to the role of the exit channel coupling in the predissociation dynamics. The results highlight the need for more sophisticated quantum dynamical calculations to describe the correlated fine structure branching ratios in this system.