Off-resonance NOVEL

Jain, Sheetal K.; Mathies, Guinevere; Griffin, Robert G.

Off-resonance NOVEL

Dateien

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Datum

2017

Autor:innen

Jain, Sheetal K.

Mathies, Guinevere

Griffin, Robert G.

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Chemie

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

The Journal of Chemical Physics. 2017, 147(16), 164201. ISSN 0021-9606. eISSN 1089-7690. Available under: doi: 10.1063/1.5000528

Zusammenfassung

Dynamic nuclear polarization (DNP) is theoretically able to enhance the signal in nuclear magnetic resonance (NMR) experiments by a factor γ_e/γ_n, where γ’s are the gyromagnetic ratios of an electron and a nuclear spin. However, DNP enhancements currently achieved in high-field, high-resolution biomolecular magic-angle spinning NMR are well below this limit because the continuous-wave DNP mechanisms employed in these experiments scale as ω_−n⁰ where n ~ 1–2. In pulsed DNP methods, such as nuclear orientation via electron spin-locking (NOVEL), the DNP efficiency is independent of the strength of the main magnetic field. Hence, these methods represent a viable alternative approach for enhancing nuclear signals. At 0.35 T, the NOVEL scheme was demonstrated to be efficient in samples doped with stable radicals, generating 1H NMR enhancements of ~430. However, an impediment in the implementation of NOVEL at high fields is the requirement of sufficient microwave power to fulfill the on-resonance matching condition, ω_0I = ω_1S, where ω_0I and ω_1S are the nuclear Larmor and electron Rabi frequencies, respectively. Here, we exploit a generalized matching condition, which states that the effective Rabi frequency, ω^eff_1S, matches ω_0I. By using this generalized off-resonance matching condition, we generate 1H NMR signal enhancement factors of 266 (~70% of the on-resonance NOVEL enhancement) with ω_1S/2π = 5 MHz. We investigate experimentally the conditions for optimal transfer of polarization from electrons to ¹H both for the NOVEL mechanism and the solid-effect mechanism and provide a unified theoretical description for these two historically distinct forms of DNP.

Fachgebiet (DDC)

540 Chemie

Schlagwörter

pulsed DNP, NOVEL, MAS NMR, trityl radicals

Zitieren

ISO 690

JAIN, Sheetal K., Guinevere MATHIES, Robert G. GRIFFIN, 2017. Off-resonance NOVEL. In: The Journal of Chemical Physics. 2017, 147(16), 164201. ISSN 0021-9606. eISSN 1089-7690. Available under: doi: 10.1063/1.5000528

BibTex

@article{Jain2017-10-28Offre-40823,
  year={2017},
  doi={10.1063/1.5000528},
  title={Off-resonance NOVEL},
  number={16},
  volume={147},
  issn={0021-9606},
  journal={The Journal of Chemical Physics},
  author={Jain, Sheetal K. and Mathies, Guinevere and Griffin, Robert G.},
  note={Article Number: 164201}
}

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