title: Cross-polarization for dissolution dynamic nuclear polarization.
abstract: Dynamic nuclear polarization (DNP) in combination with subsequent dissolution of the sample allows the detection of low-γ nuclei in the solution state with a signal gain of up to tens of thousand times compared to experiments starting from Boltzmann conditions. The long polarization build-up times of typically more than one hour are a drawback of this technique. The combination of dissolution DNP with cross-polarization (CP) in the solid state was shown to have the potential to overcome this disadvantage. In this article we discuss the cross-polarization step under dissolution DNP conditions in more detail. We show that adiabatic half-passage pulses allow us to enhance the CP efficiency in power-limited DNP probes. As a low-power alternative to Hartmann-Hahn CP we also demonstrate the applicability of frequency-swept de- and re-magnetization pulses for polarization transfer via dipolar order. We investigate the implications and restrictions of the common solid-state DNP mechanisms to the DNP-CP technique and apply a spin-thermodynamic model based on the thermal-mixing mechanism. The model allows us to investigate the dynamics of the polarization levels in a system with two nuclear Zeeman reservoirs and explains the enhanced DNP efficiency upon solvent deuteration within a spin-thermodynamic picture.
authors.affiliation: Physical Chemistry, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland. maer@ethz.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Batel
authors.forename: Alexander
authors.initials: A
authors.lastname: Däpp
authors.forename: Andreas
authors.initials: A
authors.lastname: Hunkeler
authors.forename: Beat H
authors.initials: BH
authors.lastname: Meier
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
authors.forename: Matthias
authors.initials: M
authors.lastname: Ernst
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008872:Microwaves; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D014508:Urea; C003959:TEMPO