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Issue 15, 2013
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Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

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Abstract

We systematically studied the enhancement factor (per scan) and the sensitivity enhancement (per unit time) in 13C and 29Si cross-polarization magic angle spinning (CP-MAS) NMR boosted by dynamic nuclear polarization (DNP) of functionalized mesoporous silica nanoparticles (MSNs). Specifically, we separated contributions due to: (i) microwave irradiation, (ii) quenching by paramagnetic effects, (iii) the presence of frozen solvent, (iv) the temperature, as well as changes in (v) relaxation and (vi) cross-polarization behaviour. No line-broadening effects were observed for MSNs when lowering the temperature from 300 to 100 K. Notwithstanding a significant signal reduction due to quenching by TOTAPOL radicals, DNP-CP-MAS at 100 K provided global sensitivity enhancements of 23 and 45 for 13C and 29Si, respectively, relative to standard CP-MAS measurements at room temperature. The effects of DNP were also ascertained by comparing with state-of-the-art two-dimensional heteronuclear 1H{13C} and 29Si{1H} correlation spectra, using, respectively, indirect detection or Carr–Purcell–Meiboom–Gill (CPMG) refocusing to boost signal acquisition. This study highlights opportunities for further improvements through the development of high-field DNP, better polarizing agents, and improved capabilities for low-temperature MAS.

Graphical abstract: Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

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Publication details

The article was received on 05 Jan 2013, accepted on 29 Jan 2013 and first published on 01 Feb 2013


Article type: Paper
DOI: 10.1039/C3CP00039G
Citation: Phys. Chem. Chem. Phys., 2013,15, 5553-5562
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    Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

    T. Kobayashi, O. Lafon, A. S. Lilly Thankamony, I. I. Slowing, K. Kandel, D. Carnevale, V. Vitzthum, H. Vezin, J. Amoureux, G. Bodenhausen and M. Pruski, Phys. Chem. Chem. Phys., 2013, 15, 5553
    DOI: 10.1039/C3CP00039G

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