ESR AND OPTICAL STUDIES OF O2(-) IN NAF.
CORNELL UNIV ITHACA N Y MATERIALS SCIENCE CENTER
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The O2- molecule-ion was observed as an impurity in single crystals of sodium fluoride. The ion was produced principally by room temperature x-irradiation of NaF doped with OH- ions. The O2- ion was identified by its ESR spectrum, observed at liquid helium temperatures. The g-tensor for the resonance has approximate axial symmetry about the molecular axis, with g-parallel 2.97 and g-perp. 1.41. In crystals containing isotopically enriched oxygen, the hyperfine interaction with the O17 nucleus was measured. A qualitative comparison of the ESR parameters of O2- in NaF with the determinations of the electronic structure of O2- in other alkali halides is made. The large G-shifts and the appreciable perturbation of the O2- molecular orbitals in the small NaF lattice make a quantitative treatment difficult. Optical studies of O2- in NaF were made. No absorption band in the near ultraviolet, nor fluorescence excited in that region, could be detected. An absorption at 8.7 ev was assigned to a charge-transfer band of O2-. Several other paramagnetic defects, probably associated with oxygen, were also formed in the course of the x-ray production of O2-. Their spin resonance patterns were studied but no identification was made. Author
- Solid State Physics