High-frequency pulsed ENDOR spectroscopy of the NV(-) centre in the commercial HPHT diamond.

This work reports direct 94GHz ENDOR spectroscopy of the (14)N nuclei in the NV(-) centre in single-crystal diamond. Roadmaps of ENDOR frequencies were measured and hyperfine/quadrupole interaction parameters were obtained, with AX,Y=-2.7MHz, AZ=-2.2MHz and P=-4.8MHz. The sign and value of each parameter was calculated using spin Hamiltonian matrix diagonalization, first and second order perturbation theory and confirmed experimentally. Magnetic field magnitude was measured by (13)C ENDOR signal with 0.02% precision or 0.5mT. The orientation of quadrupole, hyperfine and fine structure tensors are the same within error of experiment, g-factor is isotropic.