Investigation of Reaction Barriers in Mixed Organic Aggregates by Two‐Color Resonant Two Photon Ionization

We used two‐color resonant two‐photon ionization combined with time‐of‐flight mass spectrometry to study nucleophilic ipso‐substitution reactions with halobenzenes radical cations. Molecular clusters serve as microscopic test tubes to tackle the reactivity problem of solvated radical cations. The reaction paths – van der Waals fragmentation and chemical reaction – could be energetically separated. The substitution reactions turned out to be nearly activationless. The particularities of the excitation process are discussed.