However, the fit of a double-exponential function implicates that two T1 time constants could be appropriate to the nanodiamond samples with comparatively large size distributions, like the diamond sample MSY 0-0.150; the shorter 13 C T1 values (14-24 s) can be assigned to the smaller particles that were conceivably present in the samples. The 13 C spin-lattice relaxation measurement data acquired at two different rotor spinning rates (8 and 30 kHz) did not exhibit any appreciable variation, precluding suppression of nuclear spin diffusion by higher MAS rates for the nanoparticles and validating the effects of paramagnetic centers on the spin-lattice relaxation process of the core sp 3 carbons. The constancy of the prominent 13 C signals corroborates key contributions to the detectable 13 C signals from the core sp 3 carbons for all the nanoparticle samples under the experimental conditions. Correspondingly, the monocrystalline synthetic diamond nanomaterials used in the study exhibited the 13 C spectral fingerprints comparable to advanced diamond-based nanomaterials generated using diverse techniques .