LOCAL ELECTRONIC-STRUCTURES IN PHOSPHORUS OXYANIONS

The local electronic structure around the core-ionized phosphorus and oxygen atoms in solid phase Na3PO4, (NaPO3)n and Li3PO4 compounds has been studied by XPS and x-ray excited Auger spectroscopy. Core level a nd valence band photoelectron spectra, as well as the O KLL Auger spec tra have been measured using monochromated Al Kalpha excitation, while the high energy P KLV spectra have been excited using Mo-x-rays. From the similarity of the structures of the P KLV spectra it can be seen that the effect of the common tetrahedral symmetry is dominant while t he effect due to the change of the cation is much smaller. This observ ation is supported by comparing the respective valence band photoelect ron spectra to each other, and to the results obtained from cluster MO calculations. From the evaluation of the O KVV and O 1s spectra the o xygen Auger parameters have been derived and the 2p2p and 2s2p hole re pulsion energies have been determined for each compound. The experimen tal values of the different Auger parameter shifts (DELTAalpha', DELTA beta') place the three oxyanions into the class of oxides, hydroxides and metallic anions instead of the class of non-metallic anions and in dicates the low electronic polarizability (similar to that of SiO2) of these phosphorus oxyanions.