Photoionization energetics and dynamics of gas-phase SnCl2 by synchrotron radiation photoemission and configuration interaction calculations

The photoionization from outer- and inner-valence shells of SnCl2 vapor, induced by means of molecular effusive beam technique and dispersed synchrotron radiation as an ionizing source, reveals new spectroscopic and dynamical aspects in this molecule. Spectral features related to states with main Cl 3s contribution are observed for the first time in a molecule with Cl-metal bonds. The corresponding ionization energy (IE) is 22.61 eV. A breakdown of the one-particle model is exhibited in the inner-valence spectral region. These experimental findings are compared with the theoretical predictions obtained by performing configuration interaction (C.I.) calculations for the molecular ionic states. A strongly resonant behavior in the cross section of some main lines and satellites is experimentally pointed out by tuning the excitation photon energy through resonances localized at 25.03 and 26.11 eV. CI calculations for the transition energies relative to 4d excitations have been carried out and explain the aforementioned phenomena in terms of autoionizing 4d->LUMO lowest unoccupied molecular orbital 8b1 excitations. Finally, Auger processes following the relaxation of Sn 4d hole in the free molecule SnCl2 are observed.