The formation of O-2(-) radical anions by contact of O-2 molecules with a Na pre-covered MgO surface is studied by a combined EPR and quantum chemical approach. Na atoms deposited on polycrystalline MgO samples are brought into contact with O-2. The typical EPR signal of isolated Na atoms disappears when the reaction with O-2 takes place and new paramagnetic species are observed, which are attributed to different surface-stabilised O-2(-) raclicals. Hyperfine sublevel correlation (HYSCORE) spectroscopy allows the superhyperfine interaction tensor of O2-Na+ species to be demonstrating the direct of the O-2(-) adsorbate to determined, coordination surface Na+ cations. DFT calculations enable the structural details of the formed species to be determined. Matrix-isolated alkali superoxides are used as a standard to enable comparison of the formed species, revealing important and unexpected contributions of the MgO matrix in determining the electronic structure of the surface-stabilised Na+-O-2(-) complexes.
Napoli, F., Chiesa, M., Giamello, E., Preda, G., DI VALENTIN, C., Pacchioni, G. (2010). Formation of Superoxo Species by Interaction of O-2 with Na Atoms Deposited on MgO Powders: A Combined Continuous-Wave EPR (CW-EPR), Hyperfine Sublevel Correlation (HYSCORE) and DFT Study. CHEMISTRY-A EUROPEAN JOURNAL, 16(23), 6776-6785 [10.1002/chem.201000546].
Formation of Superoxo Species by Interaction of O-2 with Na Atoms Deposited on MgO Powders: A Combined Continuous-Wave EPR (CW-EPR), Hyperfine Sublevel Correlation (HYSCORE) and DFT Study
PREDA, GLORIA;DI VALENTIN, CRISTIANA;PACCHIONI, GIANFRANCO
2010
Abstract
The formation of O-2(-) radical anions by contact of O-2 molecules with a Na pre-covered MgO surface is studied by a combined EPR and quantum chemical approach. Na atoms deposited on polycrystalline MgO samples are brought into contact with O-2. The typical EPR signal of isolated Na atoms disappears when the reaction with O-2 takes place and new paramagnetic species are observed, which are attributed to different surface-stabilised O-2(-) raclicals. Hyperfine sublevel correlation (HYSCORE) spectroscopy allows the superhyperfine interaction tensor of O2-Na+ species to be demonstrating the direct of the O-2(-) adsorbate to determined, coordination surface Na+ cations. DFT calculations enable the structural details of the formed species to be determined. Matrix-isolated alkali superoxides are used as a standard to enable comparison of the formed species, revealing important and unexpected contributions of the MgO matrix in determining the electronic structure of the surface-stabilised Na+-O-2(-) complexes.
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