Time-resolved dynamics in large molecular cluster ions

Photoabsorption in large mass-selected cluster ions is detected via evaporation of molecules from the cluster. The shape and size evolution of the absorption spectrum with cluster size provides a mechanism to identify the chromophore and to detect the extent of charge delocalization in the cluster ion. Species reported include heterogeneous clusters of the form I2-(CO2)n, (n=0...25). Time-resolved reaction dynamics, and the breakup of the solvent shell are obtained using a picosecond laser pump-probe technique. The experimental data on I2-(CO2)16 show that the two-photon photoproducts change substantially as the delay between the pump and probe pulses is varied from 0.2-3 psec. Simple models for the intracluster dynamics will also be presented