Spectroscopic Signatures of the B and H4Polyatomic Nitrogen Aggregates in Nanodiamond

Defects within nanodiamonds have enabled a variety of quantum sensors based on optical properties that are sensitive to pressure, optical/electric fields, and the configuration of both electronic and nuclear of spins. The presence of dopants can introduce midgap states influencing their optical properties. Complex defects based on nitrogen aggregates have been shown to form in nitrogen-containing diamonds; as such, it is important to differentiate these systems from pure diamond and single nitrogen vacancy (NV) systems. Here we report the effect of N4Vx B- and H4-aggregate defects on the infrared vibrational, optical, and X-ray absorption spectroscopies of nanodiamonds. It is found that the presence of these polyatomic nitrogen-aggregate defects introduces unique vibrational responses, as well as electronic levels giving rise to unique optical and X-ray absorption features.