title: Dynamic nuclear polarization at 40 kHz magic angle spinning.
abstract: DNP-enhanced solid-state NMR spectroscopy under magic angle spinning (MAS) is rapidly developing into a powerful analytical tool to investigate the structure of a wide range of solid materials, because it provides unsurpassed sensitivity gains. Most developments and applications of DNP MAS NMR were so far reported at moderate spinning frequencies (up to 14 kHz using 3.2 mm rotors). Here, using a 1.3 mm MAS DNP probe operating at 18.8 T and ∼100 K, we show that signal amplification factors can be increased by up to a factor two when using smaller volume rotors as compared to 3.2 mm rotors, and report enhancements of around 60 over a range of sample spinning rates from 10 to 40 kHz. Spinning at 40 kHz is also shown to increase (29)Si coherence lifetimes by a factor three as compared to 10 kHz, substantially increasing sensitivity in CPMG type experiments. The contribution of quenching effects to the overall sensitivity gain at very fast MAS is evaluated, and applications are reported on a functionalised mesostructured organic-inorganic material.
authors.affiliation: Institut de Sciences Analytiques, Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), France. anne.lesage@ens-lyon.fr.
authors.forename: Sachin R
authors.initials: SR
authors.lastname: Chaudhari
authors.forename: Pierrick
authors.initials: P
authors.lastname: Berruyer
authors.forename: David
authors.initials: D
authors.lastname: Gajan
authors.forename: Christian
authors.initials: C
authors.lastname: Reiter
authors.forename: Frank
authors.initials: F
authors.lastname: Engelke
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Silverio
authors.forename: Christophe
authors.initials: C
authors.lastname: Copéret
authors.forename: Moreno
authors.initials: M
authors.lastname: Lelli
authors.forename: Anne
authors.initials: A
authors.lastname: Lesage
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley