The superoxide 0; radical ion has been generated at the surface of MgO by two different methods both involving the parallel formation of surface hydroxyls. EPR spectra at 77 K reveal the presence of only one species with a hyperfine structure due to weak dipole4ipole interaction with a nearby hydroxyl (B, = 0.37 mT, B, = 0.21 mT, B, = 0.10 mT). The set of B data is satisfactorily reproduced by a simple model for the dipolar interaction envisaging a T-shaped O;..-H species. Calculated geometrical features are in excellent agreement with a plausible structure for the superoxide species sitting on low-coordinate Mg2+ and interacting with the hydrogen of an adjacent hydroxyl.
Experimental evidence of the hyperfine interaction between a surface superoxide species on MgO and a neighbouring hydroxylic proton
GIAMELLO, Elio;UGLIENGO, Piero;
1989-01-01
Abstract
The superoxide 0; radical ion has been generated at the surface of MgO by two different methods both involving the parallel formation of surface hydroxyls. EPR spectra at 77 K reveal the presence of only one species with a hyperfine structure due to weak dipole4ipole interaction with a nearby hydroxyl (B, = 0.37 mT, B, = 0.21 mT, B, = 0.10 mT). The set of B data is satisfactorily reproduced by a simple model for the dipolar interaction envisaging a T-shaped O;..-H species. Calculated geometrical features are in excellent agreement with a plausible structure for the superoxide species sitting on low-coordinate Mg2+ and interacting with the hydrogen of an adjacent hydroxyl.
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