Communication: state mixing by spin-orbit coupling in the anionic chloroiodine dissociations.

Three spin-orbit states, 1(2)Π1/2, 2(2)Π3/2, and 2(2)Π1/2, of chloroiodine anion (ICl(-)) formed by low-energy electron attachment in the Franck-Condon region are associated with the dissociative limits of I(-) ((1)S0) and Cl ((2)P3/2) or Cl(*) ((2)P1/2) fragments. Within the adiabatic scheme, the presumptive Π-symmetry of the fragment angular distributions is dramatically changed to be the Π-Σ mixing symmetry, due to the significant spin-orbit interaction effect on the electronic state couplings of ICl(-). The present experimental approach also enables us to separate the contributions of different electronic states from the mixed states, providing a crucial method for quantitatively evaluating the configuration-interaction wavefunctions.