Time-Resolved Two-Laser Probe of Cr(CO)6 Photodissociation Dynamics

Article abstract of DOI:10.1021/j100195a003

We have examined the photodissociation of jet-cooled Cr(CO)6 using a time-resolved, two-laser multiphoton dissociation (MDP) technique with fluorescence detection of the atomic photofragments.We have observed that the rate of appearance of Cr(CO)4 via 248-nm photolysis of Cr(CO)6 is slower if the Cr(CO)6 has first been cooled in a supersonic expansion.We suggest the difference in the observed rates is due to slower internal conversion in the transient Cr(CO)5 following impulsive loss of the first CO ligand from the jet-cooled hexacarbonyl.The internal conversion is thought to be facilitated by low-energy OC-Cr-CO bending modes, which are probably not accessible by one-photon absorption from the ground state of Cr(CO)6.We discuss the utility of our time-resolved MDP/atomic fluorescence technique as a general dynamical probe for metal carbonyl photodissociation.