13C hyperfine structure and relaxation times of the P1 centre in diamond

Abstract

EPR measurements are reported for isolated nitrogen atoms substituted for carbon atoms in type-1A diamonds. The EPR lines are exceptionally narrow, (7.5+or-0.4) mu T. The relaxation times measured by continuous saturation methods are T₁T₂=(2,4+or-1.1)*10^-9 s², T₂>or=(0.87+or-0.05) mu s, T₁13C interactions reported previously as being isotropic, are shown to be axially symmetric with a=+or-(0.92+or-0.02) mT, b=+or-(0.04+or-0.01) mT and a=+or-(0.437+or-0.005) mT, b=+or-(0.039+or-0.003) mT where a, b are respectively the isotropic and anisotropic contributions to the hyperfine splitting. Three weaker ¹³C interactions have also been measured; sites are suggested for the nuclei responsible.