Velocity Map Imaging of Weakly- or Quasi-bound Autodetached Electrons in Transient Complex Anions

Some classes of reaction complexes, such as hydrogen abstraction reaction complexes, possess transient dipole moments sufficiently large to support a dipole bound electron, forming a weakly-bound transient anion.  An example is the abstraction of hydrogen from an alkene by the hydroxyl radical.  We describe how we have prepared these neutral reaction complexes by photodetachment of the stable ion-molecule complex formed between the hydroxide anion and alkenes.  Detaching near threshold leads to the creation of a transient dipole-bound anion state of the complex as H-abstraction proceeds. Using velocity map imaging of the electrons that are ejected along the reaction path, discrete kinetic energies of the electrons encode the vibrational states populated in the final radical products.  Velocity map imaging therefore is a powerful tool for studying these transient complexes.