title: Liquid state DNP of water at 9.2 T: an experimental access to saturation.
abstract: We have performed liquid state ("Overhauser") Dynamic Nuclear Polarization (DNP) experiments at high magnetic field (9.2 T, corresponding to 260 GHz EPR and 400 MHz (1)H-NMR resonance frequency) on aqueous solutions of (14)N-TEMPOL nitroxide radicals. Integrated signal enhancements exceeding -80 were observed for the water protons at microwave superheated temperatures (160 °C) and still -14 at ambient temperatures (45 °C) relevant to biological applications. Different contributions contributing to the DNP enhancement such as saturation factor, leakage factor and sample temperature under microwave irradiation could be determined independently for a high spin concentration of 1 M, allowing the calculation of the coupling factors as a function of temperature and a quantitative comparison of this parameter with values derived from field dependent relaxation measurements or predictions from MD simulation.
authors.affiliation: Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe-University, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany.
authors.forename: Petr
authors.initials: P
authors.lastname: Neugebauer
authors.forename: Jan G
authors.initials: JG
authors.lastname: Krummenacker
authors.forename: Vasyl P
authors.initials: VP
authors.lastname: Denysenkov
authors.forename: Giacomo
authors.initials: G
authors.lastname: Parigi
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Prisner
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry*; D060526:Magnetic Fields; D008872:Microwaves; D056004:Molecular Dynamics Simulation; D009584:Nitrogen / Q000737:chemistry; D009589:Nitrogen Oxides / Q000737:chemistry; D013113:Spin Labels; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D003497:Cyclic N-Oxides; D009589:Nitrogen Oxides; D013113:Spin Labels; D014867:Water; C039900:nitroxyl; D009584:Nitrogen; C001803:tempol