title: Continuous re-hyperpolarization of nuclear spins using parahydrogen: theory and experiment.
abstract: The continuous re-hyperpolarization of nuclear spins in the liquid state by means of parahydrogen (para-H2) and chemical exchange at low magnetic fields was recently discovered and offers intriguing perspectives for many varieties of magnetic resonance. In this contribution, we provide a theoretical assessment of this effect and compare the results to experimental data. A distinct distribution of polarization is found, which shares some features with experimental data and, interestingly, does not directly correspond to the loss of the singlet order of para-H2. We derived expressions for the magnetic field and para-H2-substrate interaction time, for which the polarization transfer is maximal. This work sheds light onto the effect of continuous hyperpolarization and elucidates the underlying mechanism, which may facilitate the development of an optimized catalyst. As an application, continuous hyperpolarization may enable highly sensitive nuclear magnetic resonance at very low magnetic fields, for example, for the cost-efficient screening of drugs.
authors: German Consortium for Cancer Research (DKTK), Heidelberg, Germany; Medical Physics, Department of Radiology, University Medical Center Freiburg, 79098 Freiburg (Germany); German Cancer Research Center (DKFZ), Heidelberg, Germany. jan.hoevener@uniklinik-freiburg.de.
authors: Jan-Bernd
authors: JB
authors: Hövener
authors: Stephan
authors: S
authors: Knecht
authors: Niels
authors: N
authors: Schwaderlapp
authors: Jürgen
authors: J
authors: Hennig
authors: Dominik
authors: D
authors: von Elverfeldt
mesh_terms: D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D006859:Hydrogen
keywords: NMR spectroscopy; drug detection; hyperpolarization; magnetic resonance imaging; parahydrogen