title: Electronic signatures of a model pollutant-particle system: chemisorbed phenol on TiO₂(110).
abstract: Environmentally persistent free radicals (EPFRs) are a class of composite organic/metal oxide pollutants that have recently been discovered to form from a wide variety of substituted benzenes chemisorbed to commonly encountered oxides. Although a qualitative understanding of EPFR formation on particulate metal oxides has been achieved, a detailed understanding of the charge transfer mechanism that must accompany the creation of an unpaired radical electron is lacking. In this study, we perform photoelectron spectroscopy and electron energy loss spectroscopy on a well-defined model system-phenol chemisorbed on TiO2(110) to directly observe changes in the electronic structure of the oxide and chemisorbed phenol as a function of adsorption temperature. We show strong evidence that, upon exposure at high temperature, empty states in the TiO2 are filled and the phenol HOMO is depopulated, as has been proposed in a conceptual model of EPFR formation. This experimental evidence of charge transfer provides a deeper understanding of the EPFR formation mechanism to guide future experimental and computational studies as well as potential environmental remediation strategies.
authors.affiliation: †Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803, United States.|‡Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, United States.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Patterson
authors.affiliation: ‡Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, United States.
authors.forename: Chad A
authors.initials: CA
authors.lastname: Thibodeaux
authors.affiliation: §Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, Louisiana 70806, United States.
authors.forename: Orhan
authors.initials: O
authors.lastname: Kizilkaya
authors.affiliation: †Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803, United States.|§Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, Louisiana 70806, United States.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kurtz
authors.affiliation: ‡Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, United States.
authors.forename: E D
authors.initials: ED
authors.lastname: Poliakoff
authors.affiliation: †Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803, United States.
authors.forename: Phillip T
authors.initials: PT
authors.lastname: Sprunger
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D019800:Phenol / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D014025:Titanium / Q000737:chemistry*
chemical_list: D010636:Phenols; C009495:titanium dioxide; D019800:Phenol; D014025:Titanium