PREDISSOCIATION AND ROTATIONAL ENERGY TRANSFER IN CH $B^{2}\Sigma^{+} (\nu^{\prime}=0, N^{\prime}>14; \nu^{\prime}=1, N^{\prime}>6)$

1. N. Elander, M. Hehenberger, and P. R. Bunker, Phys. Scripta 20, 631 (1979). Supported by the Physical Sciences Department of the Gas Research Institute.Author Institution: SRI International, Menlo Park, CA 94025.Fluorescence lifetimes have been determined for individual rotational levels near the predissociation limit in the $B^{2}\Sigma^{+}$ state of CH. The method is a measurement of relative quantum yields from laser-induced fluorescence intensities in a low pressure methane/oxygen flame. Levels studied are $N^{\prime} = 15$ to 17 in $\nu^{\prime} = 0, and N^{\prime} = 7$ and 8 in \nu^{\prime} = 1$. The collision free lifetimes decrease very quickly with increasing $N^{\prime}$: for example, in $\nu^{\prime} = 0, \tau(N^{\prime} = 15) = 150$ ns and $\tau (N^{\prime} = 17) \sim 1$ ns. Theoretical $calculations^{1}$ agree well with these results. The competition between collisional, predissociative, and radiative processes has been studied for these peculiar rotational levels, and a model for state-specific rotational energy transfer has been tested in this electronic state