Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
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Previous studies in UHV (Ultra High Vacuum) on the reactivity/oxidation and nature of Fe and S-species on the pyrite FeS2 (100) surface has been carried out on surfaces produced by cleavage or surfaces cleaned by ion-bombardment and annealing. These methods induce d efects at the pyrite FeS2 (100) surface and these defects influence the initial surface chemistry of pyrite. To properly address the question of the relationship between defects and reactivity and the nature of different Fe- and S-species at the surface it is preferable to find a way to under high control manipulate the surface. We have for the first time produced defect-free pyrite FeS2 (100) and been able to control and in detail characterize the S-species at the surface. We have thus been able to study the influence of variable amounts of defects on the initial surface chemistry of pyrite FeS2 (100) to obtain insight in oxidation mechanisms which still are not well understood. |
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Pyrite-structured
FeS2 or "fools gold" is the wor
lds
most abundant near-earth-crust sulphide mineral and is found in
large quantities in sulphide mineral ores of precious metals. Its
abundance in nature (in soils and natural waters) makes it relevant
to study in an environmental context. One of the major environmental
issues related to pyrite stems from the fact that pyrite is a major
source of acid mine-drainage due to mobilization of sulfuric acid
and ferrous iron upon surface oxidation in aqueous systems.