Chemical Activation of Ultrastable Alcohol Terminated HPHT Nanodiamond Surfaces Using a Brominated Intermediate

High-pressure high-temperature nanoscale diamond (ND) is the most common host of the nitrogen vacancy center (NVC) for magnetometry and electric field sensing applications. Limiting advancements in NVC charge state control and atomic/molecular control of the diamond surface are the limited chemical routes to removing C-O bonds after aerobic oxidation protocols. Bromination of the ND surface is a robust route for chemical activation using SOBr₂. Previous discoveries about the highly labile C-Br bond on the diamond surface revealed that catalysis-free C-N bond formation was possible at 25^oC and is due to the lability of the alkyl-bromide and a long-lived reactive intermediate. Here we expand the available bond formation chemistry using the reactive C-Br intermediate to generate new C-N and C-C bonds with amines and carbenes. Atomic and molecular details of the diamond surface are confirmed with vibrational spectroscopy and synchrotron-based X-ray spectroscopies. The removal of the highly stable C-O bond allows tunablility of the surface dipole moment with carbon-carbon and carbon-heteroatom bonding environments. The modulation of the surface dipole moment change the depletion and accumulation layer properties of the diamond host and was confirmed with work function measurements. These discoveries are applicable to researchers investigating the modulation of NVC (or other colour centers) photophysics and their use as a biolabeling and quantum sensor nanoprobe.