AVS 49th International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThM

Paper AS-ThM9
Valence Band X-ray Photoelectron Spectroscopy Studies of Different Forms of Sodium Phosphate

Thursday, November 7, 2002, 11:00 am, Room C-106

Session: Practical Surface Science I
Presenter: A.L. Asunskis, Kansas State University
Authors: A.L. Asunskis, Kansas State University
P.M.A. Sherwood, Kansas State University
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Valence band X-ray photoemission can be used to identify subtle differences in surface chemistry. There are a very large number of phosphate species, and it is often important to distinguish between these species. Our group has been examining phosphate surfaces on metals, and has shown@footnote 1@ that it is possible to prepare oxide-free phosphate films on the surfaces of a variety of metals (e.g. iron, aluminum, copper, and titanium) by treatment of the oxide-free metal surface with orthophosphoric acid. Studies of core X-ray photoelectron spectroscopy (XPS) are of little value in distinguishing between different phosphate species. We have shown that it is possible to distinguish between orthophosphate and metaphosphate from differences in the valence band region which can be understood by comparison with spectra predicted by band structure calculations. In this presentation we report the extension of our earlier studies to include linear phosphates of different chain length and other phosphate species. The spectra show that valence band XPS can be used to distinguish between these species and that the spectral differences can be interpreted by spectra predicted by band structure calculations. This material was based upon work supported by the National Science Foundation under grant No. CHE-0137502. @FootnoteText@ @footnote 1@ J.A. Rotole and P.M.A. Sherwood, Chem. Mater., 13, 3933-3942 (2001).