PHOTODISSOCIATION OF CORE EXCITED MOLECULES

We review several aspects of the fragmentation of photoexcited molecules near shallow core edges especially in polyatomic systems, because of possible site selective processes. We analyse the role of repulsive states of the core excited species itself and of the residual doubly charged molecular ion, using recent experiments on CH3Br photoexcited near the bromine 3d edge, as an example. We also show how potential wells in the potential surface of such doubly charged ions can lead to unexpected bond breaking on the basis of recent theoretical calculations on N2O2+. Finally, we discuss possible localisation or Coulomb explosion mechanisms and some of the limitations of site selective fragmentation processes using some recent experimental results on the BrF2C-CF2I molecule. © 1990.