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 spin system magnetic fields of 350–400 mT. In sample, enhanced up 0.12 % through direct electron-to-13C transfer without performing 1H followed 1H−13C cross-polarization. addition, ISE has been successfully applied naturally abundant a microdiamond sample 0.01 %. To characterize buildup polarization, we discuss efficiencies between as well that 13C−13C diffusion, examining various parameters which are beneficial or detrimental for successful bulk polarization.