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Naoki Komatsu 1 , Marc Dubois 2 , Katia Guérin 2 , André Hamwi 2 ,

T 1 = f°( n ) . d = f°(T). s. s. = 11.15 kJ.mol -1. Hz 2. SOLID STATE NMR STUDY OF CARBON NANODIAMONDS PRODUCED BY DETONATION TECHNIQUE. Naoki Komatsu 1 , Marc Dubois 2 , Katia Guérin 2 , André Hamwi 2 , Jérôme Giraudet 3 , Françis Masin 3

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Naoki Komatsu 1 , Marc Dubois 2 , Katia Guérin 2 , André Hamwi 2 ,

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  1. T1 = f°(n) d = f°(T) s s = 11.15 kJ.mol-1 Hz2 SOLID STATE NMR STUDY OF CARBON NANODIAMONDS PRODUCED BY DETONATION TECHNIQUE Naoki Komatsu1, Marc Dubois2, Katia Guérin2, André Hamwi2, Jérôme Giraudet3, Françis Masin3 1ShigaUniversity 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 T1 and T2 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. Physico-chemical properties Synthesis 1H : 500.33 or 300.13 MHz 13C : 125.81 or 75.47 MHz EPR NMR NDs were obtained by detonation after disintegration CP MAS 13C 8 kHz MAS 1H sp3 C sp3 C MAS 13C 8 kHz CH <F> = 30 nm CH2 2 lines N2 adsorption at 77 K BET surface : 272 m2/g C-OH O2 effect 0 kHz 7.2 nm sp2 C 8 kHz DHPP = 9.8 G g = 2.0036 Lorentzian Ns = 6.0 1017 spin.g-1 + 10% (after out-gassing) d /TMS (ppm) d /TMS (ppm) d /TMS (ppm) Nuclear relaxation Saturation recovery sequenceSpin-lattice relaxation time T1 M(t) exp((-t/CT)b) CT relaxation coefficient b= 0.6 ± 0.07 13C : 125.8175.47MHz H H H H H Acid Washing Disintegration Diamond core OH [1,2] H PC Two-dimensional 1H-13C cross polarization wide-line separation (CP-WISE) Nuclear Magnetization recovery Effect of Paramagnetic Centers (PC) on the relaxation [3] 80 exp[- Ata] T1,T2 = f°(T) 2 1H types 60 13C a≈ 0.5 D ≈ 3 13C (ppm / TMS) (F2) Homogeneous distribution of PC and nuclei a = D/6 (arbitrary space dimension D) 40 20 Inhomogeneous distribution of PC and nuclei a = 0.666 = (D+d)/6[4] (d=1) Subsystems packed in a d-dimension space 1H (Hz) (F1) Short T1 : 1.8 +/- 0.3 ms C-OH Long T1 : 61 +/- 10 ms CH2 [5] Freezing 1H • H ≈g2h02 • g : magnetogyric constant of 1H • h0 : amplitude of the fluctuating magnetic field, • : nuclear spin resonance frequency t : correlation time. • E : activation energy (Arrhenius law) T1 on first spinning band 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. Diamond core (sp3-carbons) not covered by a sp2-carbon fullerene like shell Homogeneous distribution of PC Relaxation processes differ for 1H and 13C Molecular motion paramagnetic centers C°

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