@article{eb1b3b19afe641b8a6444ce5ec801a88,
title = "Room-temperature hyperpolarization of polycrystalline samples with optically polarized triplet electrons: pentacene or nitrogen-vacancy center in diamond?",
abstract = "We demonstrate room-temperature 13C hyperpolarization by dynamic nuclear polarization (DNP) using optically polarized triplet electron spins in two polycrystalline systems: pentacene-doped [carboxyl-13C] benzoic acid and microdiamonds containing nitrogen-vacancy (NV-) centers. For both samples, the integrated solid effect (ISE) is used to polarize the 13C spin system in magnetic fields of 350-400 mT. In the benzoic acid sample, the 13C spin polarization is enhanced by up to 0.12 % through direct electron-to-13C polarization transfer without performing dynamic 1H polarization followed by 1H-13C cross-polarization. In addition, the ISE has been successfully applied to polarize naturally abundant 13C spins in a microdiamond sample to 0.01 %. To characterize the buildup of the 13C polarization, we discuss the efficiencies of direct polarization transfer between the electron and 13C spins as well as that of 13C-13C spin diffusion, examining various parameters which are beneficial or detrimental for successful bulk dynamic 13C polarization.",
author = "Koichiro Miyanishi and Segawa, {Takuya F.} and Kazuyuki Takeda and Izuru Ohki and Shinobu Onoda and Takeshi Ohshima and Hiroshi Abe and Hideaki Takashima and Shigeki Takeuchi and Shames, {Alexander I.} and Kohki Morita and Yu Wang and So, {Frederick T.K.} and Daiki Terada and Ryuji Igarashi and Akinori Kagawa and Masahiro Kitagawa and Norikazu Mizuochi and Masahiro Shirakawa and Makoto Negoro",
note = "Funding Information: Financial support. This research has been supported by the Ministry of Education, Culture, Sports, Science and Technology (grant nos. JPMXS0120330644, JPMXS0118067634, and JP-MXS0118067395), the Precursory Research for Embryonic Science and Technology (grant nos. JPMJPR1666, JPMJPR18G5, and PMJPR18G1), the Branco Weiss Fellowship – Society in Science, the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant no. 19J10976), and the Core Research for Evolutional Science and Technology (JST CREST) (grant no. JPMJCR1873). Funding Information: Acknowledgements. This work is supported by MEXT Quantum Leap Flagship Program (MEXT Q-LEAP), PRESTO, and Osaka University{\textquoteright}s International Joint Research Promotion Program. Takuya F. Segawa is grateful to the Branco Weiss Fellowship – Society in Science, administered by the ETH Zurich, and Masahiro Shirakawa for hosting him as a Guest Research Associate at Kyoto University. Koichiro Miyanishi is supported by JSPS KAKENHI and the Program for Leading Graduate Schools: Interactive Materials Science Cadet Program. Kazuyuki Takeda is supported by JST CREST. Publisher Copyright: {\textcopyright} Author(s) 2021",
year = "2021",
month = jan,
day = "1",
doi = "10.5194/mr-2-33-2021",
language = "English",
volume = "2",
pages = "33--48",
journal = "Magnetic Resonance",
issn = "2699-0059",
publisher = "Copernicus Publications",
number = "1",
}