| AVS 54th International Symposium | |
| Surface Science | Thursday Sessions |
| Session SS1-ThA |
| Session: | Environmental Surfaces |
| Presenter: | V.H. Grassian, University of Iowa |
| Authors: | J. Baltrusaitis, University of Iowa V.H. Grassian, University of Iowa |
| Correspondent: | Click to Email |
Reactions of sulfur dioxide under ambient conditions on environmentally important interfaces - calcium carbonate and iron oxide - single crystal and particle surfaces - have been investigated. A custom-designed X-ray Photoelectron Spectroscopy (XPS) ultra-high vacuum chamber is coupled to an environmental reaction chamber so that the effects of adsorbed water and molecular oxygen on the reaction chemistry can be followed. Atomic force microscopy provides additional spatial details about the reaction chemistry. It is determined that both the extent of reaction, the chemical speciation, which includes adsorbed sulfite and adsorbed sulfate, and reaction mechanisms are controlled by the environmental conditions. In addition, the two interfaces behave quite differently. Adsorbed water plays a key role in reactions of sulfur dioxide on calcium carbonate but not on iron oxide whereas molecular oxygen enhances the extent of reaction of sulfur dioxide on iron oxide but not calcium carbonate. Mechanisms to explain the reaction chemistry of sulfur dioxide on these two important environmental interfaces under different conditions are proposed. Atmospheric and environmental implications of these reactions are also discussed.