TY - JOUR
T1 - Factors affecting DNP NMR in polycrystalline diamond samples
AU - Casabianca, Leah B.
AU - Shames, Alexander I.
AU - Panich, Alexander M.
AU - Shenderova, Olga
AU - Frydman, Lucio
N1 - Israel Science Foundation (ISF) [447/09]; ERC [246754]; Perlman Family Foundation; U.S. National Science Foundation [OISE-0965137]; United States-Israel Educational Foundation/Fulbright commission in Israel; Helen and Kimmel Award for Innovative InvestigationThis research was supported by the Israel Science Foundation (ISF 447/09), ERC Advanced Grant No. 246754, a Helen and Kimmel Award for Innovative Investigation, and the generosity of the Perlman Family Foundation. We thank B. Zousman (Ray Techniques Ltd., Jerusalem, Israel), E. Osawa (NanoCarbon Research Institute, Shinshu Universtiy, Nagano, Japan), and A. Ya. Vul' and V. Yu. Osipov (Ioffe Physical-Technical Institute, St. Petersburg, Russia) for providing various diamond samples. L.B.C. acknowledges postdoc fellowships from the U.S. National Science Foundation (Grant No. OISE-0965137) and the United States-Israel Educational Foundation/Fulbright commission in Israel.
PY - 2011/10/6
Y1 - 2011/10/6
N2 - This work examines several polycrystalline diamond samples for their potential as polarizing agents for dynamic nuclear polarization (DNP) in NMR. Diamond samples of various origin and particle sizes ranging from a few nanometers to micrometers were examined by EPR, solid-state NMR and DNP techniques. A correlation was found between the size of the diamond particles and the electron spin-lattice relaxation time, the 13C nuclear spin-lattice relaxation times in room temperature magic-angle-spinning experiments, and the ability of the diamond carbons to be hyperpolarized by irradiating unpaired electrons of inherent defects by microwaves at cryogenic temperatures. As the size of the diamond particles approaches that of bulk diamond, both electron and nuclear relaxation times become longer. NMR signal enhancement through DNP was found to be very efficient only for these larger size diamond samples. The reasons and implications of these results are briefly discussed, in the light of these EPR, DNP, and NMR observations.
AB - This work examines several polycrystalline diamond samples for their potential as polarizing agents for dynamic nuclear polarization (DNP) in NMR. Diamond samples of various origin and particle sizes ranging from a few nanometers to micrometers were examined by EPR, solid-state NMR and DNP techniques. A correlation was found between the size of the diamond particles and the electron spin-lattice relaxation time, the 13C nuclear spin-lattice relaxation times in room temperature magic-angle-spinning experiments, and the ability of the diamond carbons to be hyperpolarized by irradiating unpaired electrons of inherent defects by microwaves at cryogenic temperatures. As the size of the diamond particles approaches that of bulk diamond, both electron and nuclear relaxation times become longer. NMR signal enhancement through DNP was found to be very efficient only for these larger size diamond samples. The reasons and implications of these results are briefly discussed, in the light of these EPR, DNP, and NMR observations.
UR - http://www.scopus.com/inward/record.url?scp=80053530291&partnerID=8YFLogxK
U2 - https://doi.org/10.1021/jp206167j
DO - https://doi.org/10.1021/jp206167j
M3 - Article
SN - 1932-7447
VL - 115
SP - 19041
EP - 19048
JO - Journal of Physical chemistry c
JF - Journal of Physical chemistry c
IS - 39
ER -