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Updated: Feb 28, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Anisotropic longitudinal electronic relaxation affects DNP at cryogenic temperatures
E M M Weber1, H Vezin, J G Kempf
1Département de Chimie, Ecole Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Laboratoire des Biomolécules (LBM), 24 rue Lhomond, 75005 Paris, France. kurzbach@ens.fr daniel.abergel@ens.fr.
Abstract:
We report the observation of anisotropic longitudinal electronic relaxation in nitroxide radicals under typical dynamic nuclear polarization conditions. This anisotropy affects the efficiency of dynamic nuclear polarization at cryogenic temperatures of 4 K and high magnetic fields of 6.7 T. Under our experimental conditions, the electron paramagnetic resonance spectrum of nitroxides such as TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) is only partly averaged by electronic spectral diffusion, so that the relaxation times T1e(ω) vary across the spectrum. We demonstrate how the anisotropy of T1e(ω) can be taken into account in simple DNP models.
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