Purnell, Ian J., Chiesa, Mario, Farley, Robert D., Murphy, Damien Martin  ORCID: https://orcid.org/0000-0002-5941-4879, Rowlands, Christopher C., Paganini, Maria Cristina and Giamello, Elio
2002.
Heterogeneity of surface colour centres on alkaline earth metal oxides as revealed through EPR/ENDOR spectroscopy.
Magnetic Resonance in Chemistry
40
(6)
, pp. 381-386.
10.1002/mrc.1028
|
Abstract
A variety of surface anion vacancies, or point defects, are created by high-temperature activation of a series of polycrystalline alkaline earth metal oxides (MgO, CaO and SrO). Subsequent UV irradiation of the activated oxide under a hydrogen atmosphere results in the generation of surface colour centres [FS +(H)], by electron trapping at these anion vacancies. The paramagnetic properties of these colour centres were studied by EPR and ENDOR spectroscopy. 1H ENDOR spectroscopy revealed that a well defined heterogeneity of trapped electron species exists on each oxide surface, as characterized by the different superhyperfine couplings between the trapped electron and the nearby proton of the FS + (H) centre. On MgO and CaO two dominant FS + (H) centres were identified (labelled sites I and II) whereas on SrO three FS + (H) species were found (sites I, II and III). The possible surface sites responsible for electron stabilization are discussed, and include a 3Ccornermono-vacancy, a 4Cmono-vacancy and an anion–cation di-vacancy. The results indicate that regardless of the oxide used, a common degree of morphological similarities exists on each oxide.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Chemistry |
| Subjects: | Q Science > QD Chemistry |
| Publisher: | Wiley-Blackwell |
| ISSN: | 0749-1581 |
| Last Modified: | 24 Oct 2022 11:32 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/48501 |
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