Electronic structure of substitutional nitrogen impurity in TiO₂ studied by the β-NMR method

Abstract

In order to study the local electronic structure of nitrogen impurity in rutile TiO₂, we have measured double-quantum NMR spectra of short lived β-emitter ¹²N(I=1, T _1/2=11 ms) implanted into a rutile single crystal by means of the β-NMR technique. The resonance line obtained at room temperature is well accounted for by the second order shift due to the quadrupole interaction at the oxygen substitutional site. The spectrum at 25 K has shown the other lines than the central diamagnetic line shifted by 10–15 kHz to both sides, which has been already shown in the previous data obtained with a different crystal orientation and an external field. The present results supports the existence of a paramagnetic state formed by the substitutional nitrogen impurities.