ENDOR Study of a <111> Interstitial Defect in LiF

Results of (electron-nuclear double-resonance) measurements and analysis of a 111>-oriented defect in pure LiF are presented. This paramagnetic defect is produced at low temperatures by x-ray or electron irradiation. The ENDOR hyperfine constants from 11 nonequivalent sets of lattice nuclei have been obtained by fitting the ENDOR spectrum to a spin Hamiltonian. Results of this ENDOR study show that this 111> defect is equivalent to an interstitial fluorine atom that has the form of a negatively charged diatomic molecule F₂^-, centered on a negative-ion site, with its molecular axis oriented along a 111> direction.