EPFR Formation from Phenol adsorption on Al2O3and TiO2: EPR and EELS studies.
We have examined the formation of environmentally persistent free radicals (EPFRs) from phenol over alumina and titania using both powder and single-crystal samples. Electron paramagnetic resonance (EPR) studies of phenol adsorbed on metal oxide powders indicates radical formation on both titania and alumina, with both oxides forming one faster-decaying species (lifetime on the order of 50-100 hours) and one slower-decayng species (lifetimes on the order of 1000 hours or more). Electron energy loss spectroscopy (EELS) measurements comparing physisorbed phenol on single-crystal TiO2(110) to phenoxyl radicals on the same substrate indicate distinct changes in the π-π* transitions from phenol after radical formation. The identical shifts are observed from EELS studies of phenoxyl radicals on ultrathin alumina grown on NiAl(110), indicating that this shift in the π-π* transition may be taken as a general hallmark of phenoxyl radical formation.
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Matthew C
MC
Patterson
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA ; Department of Mechanical Engineering, Brigham Young University-Idaho, Rexburg, ID 83460, USA.
Nathan D
ND
Keilbart
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Lucy W
LW
Kiruri
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Chad A
CA
Thibodeaux
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Slawo
S
Lomnicki
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Richard L
RL
Kurtz
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
E D
ED
Poliakoff
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Barry
B
Dellinger
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Phillip T
PT
Sprunger