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On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid‐State and Dissolution 13 C NMR Spectroscopy
Author(s) -
Bretschneider Christian O.,
Akbey Ümit,
Aussenac Fabien,
Olsen Greg L.,
Feintuch Akiva,
Oschkinat Hartmut,
Frydman Lucio
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600301
Subject(s) - diamond , solid state nuclear magnetic resonance , paramagnetism , polarization (electrochemistry) , nuclear magnetic resonance spectroscopy , spectroscopy , chemical physics , chemistry , hyperfine structure , analytical chemistry (journal) , materials science , nuclear magnetic resonance , atomic physics , condensed matter physics , physics , organic chemistry , quantum mechanics , chromatography
Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid‐state polarization enhancement at ambient conditions, and the maximization of 13 C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's 13 C behavior in nano‐ and micro‐particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid‐state experiments. It was found that 13 C NMR signals could be boosted by orders of magnitude in either low‐ or room‐temperature solid‐state DNP experiments by utilizing naturally occurring paramagnetic P 1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin‐lattice relaxation times characteristic of diamond, coupled with a time‐independent cross‐effect‐like polarization transfer mechanism facilitated by a matching of the nitrogen‐related hyperfine coupling and the 13 C Zeeman splitting. The efficiency of this solid‐state polarization process, however, is harder to exploit in dissolution DNP‐enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed.