XPS characterization of Bi and Mn collected on atom-trapping silica for AAS

The chemical state of analyte species collected on a water-cooled silica tu be during atom-trapping atomic absorption spectrometric determination is in vestigated with the use of X-ray photoelectron spectroscopy (XPS) for Bi an d Mn. Analysis of the Bi 4f(7/2) peak reveals that the chemical state of Bi is +3 during initial trapping (before the atomization stage), but an addit ional 0-valence state of Bi is also observed after the atomization stage. W ith the use of the measured Mn 2p(3/2) binding energy together with the obs erved 3s multiplet splitting, the chemical state of Mn is determined as +2 in all stages. Together with our previous determination of 0 valence for Au , it is now postulated that the stability of certain valence states of the three elements (Au, Bi, and Mn) on the silica matrix can be correlated to t heir electrochemical reduction potentials.