Fast right-angle spinning EPR on organic radicals: Resolution enhancement and angle determination

Hessinger, Dirk; Bauer, C.; Jeschke, Gunnar; Spiess, Hans Wolfgang

doi:10.1007/bf03162309

Cited by 3 publications

(2 citation statements)

References 24 publications

(31 reference statements)

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“…Right-Angle Spinning Electron Paramagnetic Resonance (RAS-EPR) involves spinning samples around an axis perpendicular with respect to the static magnetic field. [27][28][29] This method allows one to shorten EPR acquisition times and resolve anisotropic interactions. 27,29…”

Section: Spinning Samplesmentioning

confidence: 99%

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Rotation-induced recovery and bleaching in magnetic resonance

Linde

Chinthalapalli

Carnevale

et al. 2015

Phys. Chem. Chem. Phys.

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Thurber and Tycko recently described a 'bleaching effect' that occurs in magnetic resonance when solid samples that are doped with paramagnetic agents are subjected to rotation by magic angle spinning (MAS) in a static magnetic field with a rotation period comparable to the longitudinal relaxation time T1e of the electron spins. The bleaching effect has been investigated by Thurber and Tycko in samples spinning at temperatures near 20 K in a field of 9.4 T and by Corzilius et al. near 80 K in a field of 4.9 T. In our experience, the bleaching effect is not very severe at temperatures near 100 K in a field of 9.4 T at spinning frequencies up to 12 kHz. Bleaching can partly cancel DNP enhancements that are normally evaluated by comparing signal intensities with and without microwave irradiation. The signal attenuation due to doping and sample rotation is usually not taken into consideration when defining enhancement factors. In this paper, we describe a novel observation that the rotation of glassy samples doped with lanthanides spinning at frequencies as low as 0.1 kHz can lead to a significant reduction of the spin-lattice relaxation times T1((1)H) of protons. This effect, which bears similarities with the so-called spin refrigerators, may contribute to the success of 'brute force polarization' at sample temperatures in the mK range. The acceleration of longitudinal proton relaxation also allows one to improve the signal-to-noise ratio per unit time.

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Section: Spinning Samplesmentioning

confidence: 99%

“…[27][28][29] This method allows one to shorten EPR acquisition times and resolve anisotropic interactions. 27,29…”

Section: Spinning Samplesmentioning

confidence: 99%

Rotation-induced recovery and bleaching in magnetic resonance

Linde

Chinthalapalli

Carnevale

et al. 2015

Phys. Chem. Chem. Phys.

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Distance Measurements in Solid-State NMR and EPR Spectroscopy

Jeschke

Spieß

Novel NMR and EPR Techniques

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Fast electron paramagnetic resonance magic angle spinning simulations using analytical powder averaging techniques

Saliba

Barnes

2019

The Journal of Chemical Physics

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Simulations describing the spin physics underpinning nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy play an important role in the design of new experiments. When experiments are performed in the solid state, samples are commonly composed of powders or glasses, with molecules oriented at a large number of angles with respect to the laboratory frame. These powder angles must be represented in simulations to account for anisotropic interactions. Numerical techniques are typically used to accurately compute such powder averages. A large number of Euler angles are usually required, leading to lengthy simulation times. This is particularly true in broad spectra, such as those observed in EPR. The combination of the traditionally separate techniques of EPR and magic angle spinning (MAS) NMR could play an important role in future electron detected experiments, combined with dynamic nuclear polarization, which will allow for exceptional detection sensitivity of NMR spin coherences. Here, we present a method of reducing the required number of Euler angles in magnetic resonance simulations by analytically performing the powder average over one of the Euler angles in the static and MAS cases for the TEMPO nitroxide radical in a 7 T field. In the static case, this leads to a 97.5% reduction in simulation time over the fully numerical case and reproduces the expected spinning sideband manifold when simulated with a MAS frequency of 150 kHz. This technique is applicable to more traditional NMR experiments as well, such as those involving quadrupolar nuclei or multiple dimensions.

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Fast right-angle spinning EPR on organic radicals: Resolution enhancement and angle determination

Cited by 3 publications

References 24 publications

Rotation-induced recovery and bleaching in magnetic resonance

Rotation-induced recovery and bleaching in magnetic resonance

Distance Measurements in Solid-State NMR and EPR Spectroscopy

Fast electron paramagnetic resonance magic angle spinning simulations using analytical powder averaging techniques

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