The negatively-charged nitrogen-vacancy (NV) center is the most studied optical center in diamond and is very important for applications in quantum information science. Many proposals for integrating NV centers in quantum and sensing applications rely on their tailored fabrication in ultra pure host material. In this study, we use ion implantation to controllably introduce nitrogen into high purity, low nitrogen chemical vapor deposition diamond samples. The properties of the resulting NV centers are studied as a function of implantation temperature, annealing temperature, and implantation fluence. We compare the implanted NV centers with native NV centers present deep in the bulk of the as-grown samples. The results for implanted NV centers are promising but indicate, at this stage, that the deep native NV centers possess overall superior optical properties. In particular, the implanted NV centers obtained after annealing at 2000 °C under a stabilizing pressure of 8 GPa showed an ensemble linewidth of 0.17 nm compared to 0.61 nm after annealing at 1000 °C. Over the same temperature range, the ensemble NV−/NV0 ratio increased by a factor of ∼5, although this was accompanied by an overall decrease in the NV count.

[1] The equation of state (EOS) of molten Fe-10 wt % S was investigated by means of static high-pressure density measurements using a newly developed variation of the sink/ float technique. The method involves the use of tailored density composite spheres made of Pt or WC cores and an Al 2 O 3 (ruby/sapphire) mantle as bracketing markers for comparative density measurements of liquid Fe-10 wt % S at pressures (P) up to 20 GPa and at temperatures (T) up to 2123 K. The results of isothermal compression data confirm the validity of extrapolating to 20 GPa an EOS for pressures up to 6 GPa obtained earlier by Sanloup et al. [2000] using an X-ray absorption technique. The analysis of new data obtained in the 1773-2123 K interval up to 20 GPa resulted in new EOS parameters and also revealed the need for a well-determined melt density value at 1 atm. Application of our results to the identification of composition of liquid metallic cores of Ganymede, Io, and Mars showed Fe-10 wt % S to be a possible candidate. We used different EOS formulations to extrapolate our results to the P-T conditions of the Earth's interior. For temperatures between 4773 K at the core-mantle boundary and 5973 K at the inner core boundary the extrapolation made using the Vinet EOS resulted in density values closest to the density of the core suggested by the preliminary reference Earth model.

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Ni-related optical centres in diamond are promising as alternatives to the nitrogen vacancy ͑NV͒ centre for quantum applications and biomarking. In order to achieve the reliability and reproducibility required, a method for producing the Ni-related centres in a controllable manner needs to be established. In this study, we have attempted this control by implanting high purity CVD diamond samples with Ni and N followed by thermal annealing. Samples implanted with Ni show a new Ni-related PL peak centered at 711 nm and a well known doublet at 883/885 nm along with weak NV luminescence. The optical properties of the two Ni-related defects are investigated. In particular, an excited state lifetime of the 883/885 nm peak is measured to be 11.6 ns.