1. Naoki Komatsu 1, Marc Dubois 2, Katia Guérin 2, André Hamwi 2, Jérôme Giraudet 3, Françis Masin 3 1 Shiga University of Medical Science (SUMS), Department of Chemistry, Seta, Otsu, Shiga 520-2192, Japan 2 Laboratoire des Matériaux Inorganiques (UMR CNRS 6002) Clermont Université, 24, Avenue des Landais, 63177 Aubière, France 3 Matière Condensée et Résonance Magnétique, Université Libre de Bruxelles (U. L. B.), CP 232, Boulevard du Triomphe, B-1050 Bruxelles, Belgium World-wide interest has developed over the last few years in nanostructured diamond, particularly in nanodiamonds of detonation origin since this method allows the particles to be separated into a more narrow range of particle sizes (fractionalization). Nuclear magnetic resonance (NMR) is a very useful tool in studying the structural features and determination of different allotropic forms in nanocarbons since the position of the NMR signal of each nucleus depends on the nature of chemical bonding [1,2]. Measurements of the spin-lattice and spin-spin relaxation times T 1 and T 2 yield information about the molecular motion nuclear interactions with paramagnetic centers (localized unpaired electrons) [1-3]. Methods of diamond formation can be divided tentatively into two groups. The first group comprises the methods involving the phase transition graphite → diamond. Graphite turns diamond at high temperature and pressure. The second group consists of the methods of chemical formation of diamond films; the detonation method of diamond formation was rather referred to the first group. References : [1] Shames AI, Panich AM, Kempiski W, Alexenskii AE, Baidakova MV, Dideikin AT, Yu. Osipov V, Siklitski VI, Osawa E, Ozawa M, Ya. Vul' A. J Phys. Chem. Solids, 2002 ; 63: 1993-2001 [2] Panich AM. Diamond and related Materials, 16 (2007; 2044–2049 [3] Furman GB, Kunoff EM, Goren D, Pasquier V, Tinet D. Phys. Rev. B 1995; 52 (14): 10182-10187. [4] W.E. Blumberg, Phys. Rev. 1960, 119 (1), 79-84. [5] N. Bloembergen, E. M.; Purcell, R. V. Pound, Phys. ReV. 1948, 73, 679-712. NDs were obtained by detonation after disintegration Synthesis = 30 nm Physico-chemical properties Nuclear relaxation N 2 adsorption at 77 K BET surface : 272 m 2 /g SOLID STATE NMR STUDY OF CARBON NANODIAMONDS PRODUCED BY DETONATION TECHNIQUE 7.2 nm EPR  H PP = 9.8 G g = 2.0036 Lorentzian Ns = 6.0 10 17 spin.g -1 + 10% (after out-gassing) O 2 effect NMR  /TMS (ppm) MAS 13 C 8 kHz CH 2 sp 2 C C-OH sp 3 C CH sp 3 C Diamond core Acid Washing Disintegration H H H H H OH H PC CP MAS 13 C 8 kHz  /TMS (ppm) MAS 1 H 0 kHz 8 kHz Saturation recovery sequence Spin-lattice relaxation time T 1 1 H : 500.33 or 300.13 MHz 13 C : 125.81 or 75.47 MHz 2 lines 13 C : 125.81 75.47 MHz Nuclear Magnetization recovery Effect of Paramagnetic Centers (PC) on the relaxation [3] Homogeneous distribution of PC and nuclei  = D/6 exp[- At  ]  ≈ 0.5 D ≈ 3   = f°( ) T 1, T 2 = f°(T) 13 C 1H1H Short T 1 : 1.8 +/- 0.3 ms C-OH Long T 1 : 61 +/- 10 ms CH 2 Diamond core (sp 3 -carbons) not covered by a sp 2 -carbon fullerene like shell Homogeneous distribution of PC Relaxation processes differ for 1 H and 13 C Molecular motion paramagnetic centers C° T 1 on first spinning band [1,2] M(t) exp((-t/CT)  ) CT relaxation coefficient  = 0.6 ± 0.07 Inhomogeneous distribution of PC and nuclei  = 0.666 = (D+d)/6 [4] (d=1) Subsystems packed in a d-dimension space Freezing s Hz 2 s = 11.15 kJ.mol -1 [5] H ≈  2 h 0 2  : magnetogyric constant of 1 H h 0 : amplitude of the fluctuating magnetic field,  : nuclear spin resonance frequency   correlation time. E : activation energy (Arrhenius law)  = f°(T) Two-dimensional 1 H- 13 C cross polarization wide-line separation (CP-WISE) 13 C (ppm / TMS) (F2) 1 H (Hz) (F1) 80 60 20 40 2 1 H types (arbitrary space dimension D )