Does a strong pynocline impact organic-matter preservation and accumulation in an anoxic setting ? The case of the Orca Basin, Gulf of Mexico

• Published in: Comptes Rendus Geoscience
• Main Authors: Tribovillard, Nicolas, Bout-Roumazeilles, V., Sionneau, Thomas, Montero Serrano, J.C, Riboulleau, Armelle, Baudin, François, Bout‑roumazeilles, Viviane, Serrano, Jean, Lafon, Olivier, Sofia, Aany, Thankamony, Lilly, Rosay, Melanie, Aussenac, Fabien, Lu, Xingyu, Trébosc, Julien, Vezin, Hervé, Amoureux, Jean-Paul
• Other Authors: Processus et bilan des domaines sédimentaires (PBDS), Université de Lille, Sciences et Technologies-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: Holocene; Anoxia; Organic matter preservation; Palynofacies; Clay minerals Mots clés : Holocène; Anoxie; Préservation de la matière organique; Palynofaciès; Minéraux argileux; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Orca
• Online Access: https://hal.science/hal-00371297; https://doi.org/10.1016/j.crte.2008.10.002

International audience We show how the 29 Si NMR signals of dispersed inorganic nano-particles of laponite s can be enhanced by Dynamic Nuclear Polarization (DNP). The direct DNP enhances the signals of 29 Si nuclei near unpaired electrons, whereas the indirect DNP via 1 H enhances the signals of more remote sites. As a local and non-destructive technique, solid-state nuclear magnetic resonance (NMR) provides precious insight into the atomic-scale structure and dynamics of nanoparticles (NPs), i.e. materials with three external dimensions sized between 1 and 100 nm. 1,2 Nevertheless, the low sensitivity of NMR can preclude the observation of diluted species, such as the edge, corner, grafting or surface sites. The sensitivity limitation of NMR is even more acute for nuclei with long longitudinal relaxation times (T 1n), low natural abundance and/or low gyromagnetic ratio, such as 29 Si. 3,4 Herein, we show how the NMR signals of inorganic NPs dispersed in a frozen solution containing TOTAPOL 5 can be enhanced at high static magnetic field, B 0 , and under magic-angle spinning (MAS) using dynamic nuclear polarization (DNP). 3-12 Enhancements of 29 Si NMR signals in the order of 10 are reported in direct polarization (DP) and 1 H-29 Si cross-polarization (CP) experiments for laponite s (1), an industrial synthetic clay NP (see Fig. 1), with applications for hybrid materials and soft matter (cleanser, coating). 13-15 Hereafter, the DP and CP experiments with microwave irradiation are referred to as direct and indirect DNP, respectively. This protocol should become a standard for the DNP of NPs, since they are often dispersed in a liquid phase to prevent their aggregation. 16 The dispersion is supplementary to impregnation 4,17 and co-condensation, 18 which have been employed for high-field MAS DNP of porous solids or particle aggregates. 3,4,17-19 Hitherto, dispersion in frozen 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)-propan-2-ol (TOTAPOL) solutions has only been demonstrated for indirect 13 C and 15 N DNP of biological ...