Long Spin Coherence and Relaxation Times in Nanodiamonds Milled from Polycrystalline $^{12}$C Diamond

• DOI: 10.48550/arxiv.2301.10188
• Publication Date: 2023-01-01
• Authors: James E. March; Benjamin D. Wood; Colin Stephen; Laura Durán Fervenza; Ben G. Breeze; Soumen Mandal; Andrew M. Edmonds; Daniel J. Twitchen; Matthew Markham; Oliver A. Williams; Gavin W. Morley
• Keywords: Polycrystalline diamond

The negatively charged nitrogen-vacancy centre (NV$^-$) in diamond has been utilized a wide variety of sensing applications. centre's long spin coherence and relaxation times ($T_2^*$, $T_2$ $T_1$) at room temperature are crucial to this, as they often limit sensitivity. Using NV$^-$ centres nanodiamonds allows for operations environments inaccessible bulk diamond, such intracellular sensing. We report single isotopically-purified polycrystalline ball-milled nanodiamonds. spin-locking pulse sequence, we observe times, $T_2$, up 786 $\pm$ 200 $μ$s. also measure $T_2^*$ 2.06 0.24 $μ$s $T_1$ 4.32 0.60 ms. Scanning electron microscopy atomic force measurements show that the containing NV$^{-}$ with longest time is smaller than 100 nm. EPR give an N$_{s}$$^{0}$ concentration 0.15 0.02 ppm nanodiamond sample.