Manganese speciation in exhaust particulates of automobiles using MMT-containing gasoline

XAFS spectroscopy is used to speciate Mn-containing auto exhaust particulat es emitted from MMT-added gasoline engines and collected in a controlled ma nner. A series of Mn compounds was also measured to model and aid quantific ation of the unknown species in the particulates. XANES results show that t he average Mn valence in these particulates is similar to 2.2 and that MnO, Mn3O4, MnSO4. H2O and a Mn phosphate are the predominant phases present. T he amount of each component varies depending on engine history and test cyc le. The XAFS analysis was found to corroborate the XANES results.