Multiple photofragmentation pathways with different recoil anisotropy from a metal-ion-ligand complex.

Spatial recoil anisotropy that is dependent upon the fragment-ion species is reported for the first time for a metal-ion-ligand complex after a single photoexcitation process by linearly polarized light. Upon excitation to the lowest three excited states of Mg+-ICH3, originating from the Mg+2P states, fragment ions of MgI+ and ICH+3 are found to have clear and different angular dependences, which are also characteristic of the excited states. These are explained from the results of theoretical work in that the calculated ground-state complex has a bent structure and further in that each transition dipole moment vector of the complex almost coincides with the Mg+ 3p orbital lobe direction in each case. The fragment ions are concluded to be formed along dissociative potential surfaces which are crossed by the initially excited states, in a much faster process than the rotational period of the complex.