NUCLEOPHILIC-SUBSTITUTION REACTIONS IN MOLECULAR CLUSTERS FOLLOWING PHOTOIONIZATION

Substitution reactions in mixed van der Waals aggregates consisting of halobenzenes and polar molecules are studied by resonant two-photon ionization (R2PI). Spectroscopic fingerprints in the ion yield curves of the product ions allow their neutral precursors to be assigned. Intracluster ipso substitution reactions have been found, depending both on the number and type of solvent molecules and on the halogen present. They are discussed in terms of an addition-elimination mechanism. Electron transfer is found to play an important role both in the reaction mechanism and in the size-dependent switching between redox and substitution reactions.