Regensburg 1998 – wissenschaftliches Programm
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O: Oberflächenphysik
O 32: Oberfl
ächenreaktionen (II)
O 32.12: Vortrag
Donnerstag, 26. März 1998, 19:00–19:15, H37
Reactivity of Surface Sites on fractured Pyrite — •A.G. Schaufu"s1, H.W. Nesbitt2, I. Kartio3, K. Laajalehto3, G.M. Bancroft2, and R. Szargan1 — 1University of Leipzig, Germany — 2University of Western Ontario, Canada — 3University of Turku, Finland
Synchrotron radiation excited photoelectron spectroscopy was used to monitor sulphur sites on pyrite surfaces reacted with atmospheric gases. The results demonstrate that there are at least three distinct states at the pyrite surface and each is oxidised at a different rate in the presence of these gases. The two surface sites are more reactive than bulk sulphur. It was found that the model of Nesbitt et. al. [1] that is based on different chemical states of sulphur might explain the S 2p component with the lowest binding energy to be S2− as well as the different oxidation rates of the second surface component and bulk sulphur. A model combining the interpretation of sulphur states of Nesbitt and the proposed oxidation mechanism of Eggleston et al. [2] was developed to explain the initial oxidation processes on pyrite surfaces. The oxidation seems to start with the oxidation of S2− sites followed by the oxidation of Fe(II) ions.
[1] H.W. Nesbitt, G.M. Bancroft, A.R. Pratt, M.J. Scaini, submitted to American Mineralogist
[2] C.M. Eggleston, J.-J. Ehrhardt, W. Stumm, American Mineralogist 81 1036 (1996)