High Temperature Treatment of Diamond Particles Toward Enhancement of Their Quantum Properties

Abstract

Fluorescence of the negatively charged nitrogen-vacancy (NV − ) center of diamond is sensitive to external electromagnetic fields, lattice strain, and temperature due to the unique triplet configuration of its spin states. Their use in particulate diamond allows for the possibility of localized sensing and magnetic-contrast-based differential imaging in complex environments with high fluorescent background. However, current methods of NV − production in diamond particles are accompanied by the formation of a large number of parasitic defects and lattice distortions resulting in deterioration of the NV − performance. Therefore, there are significant efforts to improve the quantum properties of diamond particles to advance the field. Recently it was shown that rapid thermal annealing (RTA) at temperatures much exceeding the standard temperatures used for NV − production can efficiently eliminate parasitic paramagnetic impurities and, as a result, by an order of magnitude improve the degree of hyperpolarization of 13 C via polarization transfer from optically polarized NV − centers in micron-sized particles. Here, we demonstrate that RTA also improves the maximum achievable magnetic modulation of NV − fluorescence in micron-sized diamond by about 4x over conventionally produced diamond particles endowed with NV − . This advancement can continue to bridge the pathway toward developing nano-sized diamond with improved qualities for quantum sensing and imaging.

Microscopic Study of Optically Stable Coherent Color Centers in Diamond Generated by High-Temperature Annealing

“…[47], but contradicts to the large raised up in ref. [48] and almost unchanged (if not decreased) in Ref [49,50]. One possible explanation is the difference in protocol.…”

“…Recently, several works have demonstrated the improvement of diamond particles via rapid thermal annealing (RTA) [47][48][49][50]. By analysing the EPR and absorption spectrum, the RTA method is shown to improve, macroscopically, the quality of diamond particles.…”

“…In our work, there is no pronounced enhancement on the T 1 time, while in ref. [48][49][50] T 1 are significantly improved. This may related to the recovery from lattice damages induced by the e-beam irradiation and during nanodiamond fabrication.…”

Advances in the Surface Functionalization of Nanodiamonds for Biological Applications: A Review

“…41,46,86 Figure 2 demonstrates a variety of functional groups, such as amino, phosphate, azide, halogen, silica, and polymers, that can be anchored covalently Scheme 1. Chemical Reactions to Purify and Homogenize the Surface of NDs: Surface Homogenization through Carboxylation (2), 60 Hydroxylation (3 and 5), 73,74 Hydrogenation (4), 76,77 and Thermal Annealing (5) 69,70 ACS Applied Nano Materials to the ND surface, both for the DND and HPHT types, to facilitate further functionalization with biomolecules or macromolecules. Noncovalent attachment is an alternative and effective procedure to functionalize NDs and is commonly used to conjugate proteins, metals, drugs, polymers, and lipids.…”

“…Acid treatment (Scheme , 2 ) is also a critical step in the processing of HPHT NDs. In some cases, HPHT NDs undergo high-temperature (>800 °C) annealing to assist in the formation of optical color centers. , This annealing step often leads to sp 3 -to-sp 2 carbon transformation (Scheme , 5 ), which can be utilized for further ND functionalization; , however, removal of the sp 2 carbon is essential for the majority of applications. Acid treatments similar to those mentioned for DND act to remove the sp 2 carbons from the surface of HPHT NDs, oxidize the surface, and generate a higher ratio of carboxyl groups (Scheme , 2 ).…”