Bottom up molecular doping approach to synthesizing HPHT color centers in nanostructured diamond*

Diamond nanocrystals are advantageous for a myriad of biological and technological applications because its optical color centers are tunable between the ultraviolet and near-infrared (NIR) spectral regions. Our work describes a molecular approach to dope diamond nanocrystals with silicon heteroatoms at extreme temperature (>1800K) and pressure (>15 GPa) conditions using argon as a near-hydrostatic pressure medium. Tetraethylorthosilicate (TEOS) molecules chemically dope an amorphous carbon aerogel during nanodiamond synthesis within a laser-heated diamond anvil cell. Pressure-dependent photoluminescence is used in tandem with ab initio quantum cluster calculations to measure the pressure dependence of the SiV- centers’ zero phonon line (λ ~ 738 nm, 0.9 meV / GPa). Aberration-corrected scanning transmission electron microscopy images heteroatoms on the surfaces and also the interiors of diamond nanocrystals. Scanning transmission x-ray absorption microscopy (STXM) measurements, along with electron energy loss spectroscopy and ab initio quantum cluster calculations, suggest a partial graphitic surface reconstruction of the diamond nanocrystals.