Dynamic nuclear polarization (DNP) is a method to transfer electron spin polarization to nuclei, enhancing the nuclear spin polarization. In theory DNP can boost the inherent low sensitivity of NMR by a factor of up to 660, estimated by the magnetic energy of electrons in thermal equilibrium.
This factor has recently been greatly improved by Makoto Negoro, Osaka University, Japan, and collaborators using a novel room temperature hyperpolarization approach. The researchers irradiated NMR samples with a pulsed laser, and chose electron spins of photo-excited triplet states for polarization transfer, instead of thermally equilibrated ones, which gave 34 % 1H spin polarization with an enhancement factor of 250,000.
While setting a new record for NMR sensitivity enhancement, this new technique can be readily applied to other, especially insensitive, nuclei, high resolution MRI and fundamental physics studies.
- Room temperature hyperpolarization of nuclear spins in bulk,
Kenichiro Tateishia, Makoto Negoroa, Shinsuke Nishidac, Akinori Kagawaa, Yasushi Moritac, Masahiro Kitagawa,
Proc. Natl. Acad. Sci. U.S.A. 2014, 111, 7527−7530.