Photofragment vector correlations as a probe of K‐scrambling in unimolecular dissociation

We discuss the relationship between fragment‐rotational polarization and the extent of K ‐mixing in an energized molecule undergoing unimolecular dissociation at fixed energy and angular momentum. Accurate measurements of the second Legendre moment of the v · j angular correlation are presented for the CN fragments produced in the photoinitiated dissociation of NCCN at 193 nm. as determined by Doppler spectroscopy using a transient frequency modulation technique. The strength of the correlation significantly exceeds what would be observed if all K states of the dissociating molecule were equally represented.