T. Minamisono et al., ELECTRIC QUADRUPOLE INTERACTIONS OF THE SHORT-LIVED BETA-EMITTER N-12IN INSULATOR CRYSTALS (N-12 IMPLANTED IN SINGLE-CRYSTAL TIO2), Zeitschrift fur Naturforschung. A, A journal of physical sciences, 53(6-7), 1998, pp. 293-300
The electronic structure of nitrogen atoms as impurities in an ionic T
iO2 crystal has been investigated by analyzing electric field gradient
s (EFGs) measured by use of short-lived beta-emitting N-12 implanted f
ollowing nuclear reactions. Conventional beta-NMR and its modification
, suitable for the detection of quadrupole effects in the NMR spectra,
were used for the investigation of hyperfine interactions of N-12 loc
ated in substitutional sites of O atoms and interstitial sites in the
crystal. In order to deduce absolute values of the EFGs from the obtai
ned eqQ/h, the quadrupole moment of N-12 has been determined from the
NMR detection of N-12 implanted in BN(hexagonal) crystal. Here the EFG
at the N atom in BN was measured by detecting the FT-NMR of N-14 in t
he crystal. The EFGs in TiO2 are compared with the theoretical predict
ions based on the nb initio band-structure calculation in the framewor
k of the KKR method.