Xiaorong Li

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


This thesis describes photoelectron spectroscopy (PES) studies with variable photon energy for organometallic molecules of late transition metals, including cobalt, rhodium, iridium, nickel, palladium, platinum, copper, and silver. Synchrotron radiation (in the range of 30 to 170 eV photon energy) and traditional helium I (21.22 eV) and helium II (40.81 eV) light sources were used in this study, with the aid of theoretical ground state and cross section calculations by using X{dollar}\alpha{dollar}-SW and Gelius model methods. With these techniques the variation of band intensities as a function of photon energy were investigated. The very different intensity features between metal d orbitals (due to delayed maximum, Cooper minimum, and p-d resonance) and ligand orbitals (a monotonic decay for carbon 2p) allowed confident assignments for the photoelectron spectra of those compounds whose PE spectra were recorded for the first time. In particular, this thesis describes attempts to resolve controversies over the PE spectral assignments for some fundamental organometallic molecules. Based on the reliable spectral assignments, a difference in metal d ionization potentials (IP) between the first and second (or third) row transition metals, which is much larger for the late transition groups than for the early transition groups, has been demonstrated. The cause of this large IP difference has been explored by comparing trends in relative intensities (branching ratios) for analogous bands in compounds of the first, second and third transition metals, and by comparing the calculated ground state energy differences of metal d based MO's with the observed IP differences. The method for analysis of the trends of band intensity was used to evaluate the difference in the ground state orbital characters. These studies show that, contrary to other reports, differential relaxation effects are not the dominant cause of the IP trends. For some compounds, the complete inner valence spectra have also been assigned with the aid of the experiments and the X{dollar}\alpha{dollar}-SW energy calculations.



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