Coincident product distributions and vector correlations in the 193 nm photodissociation of NCCN

The theory of unimolecular decomposition has played a central role in the history of chemical kinetics and molecular dynamics. Energy-dependent rate constants, product final state distributions, and photofragment excitation spectra have provided experimental tests for simple and complex unimolecular theories. The use of Doppler spectroscopy to measure correlated velocity and angular momentum distributions can frequently provide a more complete picture of the dissociation process than other, more integrated measurements. The 193 nm dissociation of cyanogen (NCCN) has been considered a classic case of a barrierless dissociation, well described by simple phase space theory, where all asymptotic product states that conserve total energy and angular momentum are considered equally likely.