Articles | Volume 1, issue 1
https://doi.org/10.5194/mr-1-75-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/mr-1-75-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Distance measurement between trityl radicals by pulse dressed electron paramagnetic resonance with phase modulation
Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
Henrik Hintz
Faculty of Chemistry and Center for Molecular Materials (CM), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
Agathe Vanas
Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
Adelheid Godt
Faculty of Chemistry and Center for Molecular Materials (CM), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
Gunnar Jeschke
Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
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Magn. Reson. Discuss., https://doi.org/10.5194/mr-2024-17, https://doi.org/10.5194/mr-2024-17, 2024
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Electron spins sense their environment via magnetic interactions. An important contribution stems from nuclear spins in their vicinity. They cause loss of coherence and thus reduce resolution of spectra obtained by experiments on electron spins and the efficiency of transferring electron-spin magentization to other nuclear spins. Here we study how protons in trityl radicals contribute to coherence loss. Such coherence loss is slower in the presence of a strong microwave field.
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Electron spin dynamics during microwave irradiation are of increasing interest in electron paramagnetic resonance (EPR) spectroscopy. Here, we show that these dynamics can be probed by modern pulse EPR experiments that use shaped microwave pulses. Combined with spin dynamics simulations, these results provide a starting point for optimizing existing EPR experiments and for developing new pulse sequences.
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Sensitivity is often the limiting factor in ENDOR. Here, we demonstrate how using chirp radiofrequency pulses can improve ENDOR sensitivity up to 3-9-fold, with the strongest increase for broader lines often encountered in disordered solids for nuclei such as nitrogen and metals. The resulting drastic speed-up in acquisition times renders also 2D ENDOR more feasible, as we demonstrate in 2D TRIPLE showing correlations of Cu hyperfine couplings.
Nino Wili, Jan Henrik Ardenkjær-Larsen, and Gunnar Jeschke
Magn. Reson., 3, 161–168, https://doi.org/10.5194/mr-3-161-2022, https://doi.org/10.5194/mr-3-161-2022, 2022
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Dynamic nuclear polarisation (DNP) transfers polarisation from electron to nuclear spins. This is usually combined with direct detection of the latter. Here, we show that it is possible to reverse the transfer at 1.2 T. This allows us to investigate the spin dynamics of nuclear spins close to electrons – something that is notoriously difficult with established methods. We expect reverse DNP to be useful in the study of spin diffusion or as a building block for more elaborate pulse sequences.
Kathrin Aebischer, Nino Wili, Zdeněk Tošner, and Matthias Ernst
Magn. Reson., 1, 187–195, https://doi.org/10.5194/mr-1-187-2020, https://doi.org/10.5194/mr-1-187-2020, 2020
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Resonant pulses in a spin-lock frame are used to select parts of the rf-field distribution in NMR experiments. Such pulses can be implemented in a straightforward way and arbitrarily shaped pulses can be used. We show an application of such pulses in homonuclear decoupling where restricting the amplitude distribution of the rf field leads to improved performance.
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Electron spins sense their environment via magnetic interactions. An important contribution stems from nuclear spins in their vicinity. They cause loss of coherence and thus reduce resolution of spectra obtained by experiments on electron spins and the efficiency of transferring electron-spin magentization to other nuclear spins. Here we study how protons in trityl radicals contribute to coherence loss. Such coherence loss is slower in the presence of a strong microwave field.
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Electron spin dynamics during microwave irradiation are of increasing interest in electron paramagnetic resonance (EPR) spectroscopy. Here, we show that these dynamics can be probed by modern pulse EPR experiments that use shaped microwave pulses. Combined with spin dynamics simulations, these results provide a starting point for optimizing existing EPR experiments and for developing new pulse sequences.
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Field: EPR | Topic: Pulse-sequence development
The decay of the refocused Hahn echo in double electron–electron resonance (DEER) experiments
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Optimising broadband pulses for DEER depends on concentration and distance range of interest
Thorsten Bahrenberg, Samuel M. Jahn, Akiva Feintuch, Stefan Stoll, and Daniella Goldfarb
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Double electron–electron resonance (DEER) provides information on the structure of proteins by attaching two spin labels to the protein at a well-defined location and measuring the distance between them. The sensitivity of the method in terms of the amount of the protein that is needed for the experiment depends strongly on the relaxation properties of the spin label and the composition of the solvent. We show how to set up the experiment for best sensitivity when the solvent is water (H2O).
Markus Teucher, Mian Qi, Ninive Cati, Henrik Hintz, Adelheid Godt, and Enrica Bordignon
Magn. Reson., 1, 285–299, https://doi.org/10.5194/mr-1-285-2020, https://doi.org/10.5194/mr-1-285-2020, 2020
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With a pulsed dipolar electron paramagnetic resonance technique named double electron–electron resonance (DEER), we measure nanometer distances between spin labels attached to biomolecules. If more than one spin type is present (A and B), we can separately address AA, AB, and BB distances via distinct spectroscopic channels, increasing the information content per sample. Here, we investigate the appearance of unwanted channel crosstalks in DEER and suggest ways to identify and suppress them.
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The determination of distance distributions in the nanometre range is an important application of pulsed electron paramagnetic resonance spectroscopy. However, low sensitivity is often a major challenge. In this paper, we compare several broadband-shaped pulses and compare their performance to classical rectangular pulses in order to increase the sensitivity of double electron–electron resonance to a commercial setup. We show that improvements in sensitivity of up to 86 % are possible.
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Wili, N.: Distance measurements between trityl radicals by pulse dressed electron paramagnetic resonance with phase modulation: Raw Data, Processing Scripts, Simulations (Version submitted version), Data set, Zenodo, https://doi.org/10.5281/zenodo.3703053, 2020. a
Short summary
Measuring distances between unpaired electron spins is an important application of electron paramagnetic resonance. The longest distance that is accessible is limited by the phase memory time of the electron spins. Here we show that strong continuous microwave irradiation can significantly slow down relaxation. Additionally, we introduce a phase-modulation scheme that allows measurement of the distance during the irradiation. Our approach could thus significantly extend the accessible distances.
Measuring distances between unpaired electron spins is an important application of electron...