Pyridine-induced formation of 17O–2 adsorbed on thermally activated CaO
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 72, 1553-1558
- https://doi.org/10.1039/f19767201553
Abstract
Whatever the pretreatment of CaO (thermal activation or γ-irradiation in the presence of H2), the molecular ion O– 2 could not be observed by direct oxygen adsorption. It was necessary to adsorb pyridine before oxygen to stabilize the molecular ion O– 2 characterised by g′zz= 2.169, g″zz= 2.093 (major site), gyy= 2.0059 and gxx= 2.0004. Using oxygen isotopically enriched in 17O, it was possible to show that the oxygen nuclei were equivalent with a hyperfine constant Axx= 76 G, while the Ayy and Azz values of the tensor were too small to be resolved. The molecular ion O– 2 was adsorbed with its internuclear axis (z) parallel to the surface plane and was shown to exchange readily with gas phase oxygen. O– 2 could be eliminated by further pyridine adsorption and restored again by a consecutive oxygen adsorption. Several such cycles could be produced easily. For the O– 2 molecular ions, the electron donor sites are thought to be the surface coordinatively unsaturated O2– ions and the adsorption sites the Ca2+ surface cations.Keywords
This publication has 0 references indexed in Scilit: