title: Topical Developments in High-Field Dynamic Nuclear Polarization.
abstract: We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including13C,2H, and17O using trityl via the cross effect. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefit of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz / 460 GHz DNP system that improves microwave delivery and increases enhancements up to 50%.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.|Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Vladimir K
authors.initials: VK
authors.lastname: Michaelis
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.|Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Ta-Chung
authors.initials: TC
authors.lastname: Ong
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Kiesewetter
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Derik K
authors.initials: DK
authors.lastname: Frantz
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Walish
authors.affiliation: Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center (CERM) University of Florence, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Ravera
authors.affiliation: Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center (CERM) University of Florence, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Swager
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.|Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Griffin
keywords: DNP; NMR; cross-effect; cryoprotection; polarizing agent; radicals