EPR data on the self-interstitial complex O3 in diamond
Abstract
A previously unreported defect, which is labeled O3, has been observed in the EPR spectrum of synthetic type-IIa diamonds irradiated at 100 K with 2 MeV electrons. This defect was not observed in identical diamonds whose temperature during electron irradiation was >=300 K. This center has also been observed in neutron irradiated natural type-Ib diamonds, but only after isochronal annealing at about 650 K: it subsequently annealed out at about 720 K. Analysis of the angular variation of the EPR line positions has determined the zero-field interaction (D), showing that the center has a triplet S=1 ground state and C2 symmetry, with a <100> rotation axis. The use of a synthetic type-IIa diamond with 5% 13C isotopic enrichment allowed observation of 13C hyperfine satellites. Analysis of the 13C hyperfine couplings by a simple molecular orbital calculation shows that 76% of the unpaired electronic wave function is localized in two nonbonding 2p orbitals, on different carbon atoms. Interpretation of the parameter D as arising primarily from dipole-dipole interaction between these two orbitals indicates that they are separated by 0.32(2) nm. The nonbonding 2p orbitals indicate the involvement of <100>-split interstitials (I100) in the structure. Two possible models are proposed, one involving two and one three parallel I100 at next-nearest-neighbor positions, of which the latter gives the better fit to the data.
- Publication:
-
Physical Review B
- Pub Date:
- September 2000
- DOI:
- 10.1103/PhysRevB.62.6587
- Bibcode:
- 2000PhRvB..62.6587H
- Keywords:
-
- 61.72.Ji;
- 61.80.Fe;
- 76.30.-v;
- 76.30.Mi;
- Point defects and defect clusters;
- Electron and positron radiation effects;
- Electron paramagnetic resonance and relaxation;
- Color centers and other defects