Gas-phase valence photoelectron spectra of Ni(II) acetylacetonate with synchrotron radiation

The photoelectron spectra (PE) for the outer-valence region of Ni(II) acetylacetonate, excited by synchrotron radiation in the 30+90 eV photon energy range, are reported and discussed. An analysis of the branching ratio of the first band as a function of photon energy confirms our previous description of the HOMO (Highest Occupied Molecular Orbital) as the b3g component of the ligand ~3 orbitals, with modest admixture of Ni dyz orbital. The whole PE spectrum has been reassigned on the ground of the observed variations in relative band intensity ratios and of deconvolution with symmetric gaussian curves. The enhancement shown by the bands in the IE region between 7.6 and 8.8 eV in the spectra taken at photon energies near the Ni 3p threshold is most likely due to resonant processes following Ni 3p---~3d excitations.