Michael Schatz, Matthias Streun, Sven Jovanovic, Rüdiger-A Eichel, Josef Granwehr
{"title":"Workflow for systematic design of electrochemical in operando NMR cells by matching <i>B</i> <sub>0</sub> and <i>B</i> <sub>1</sub> field simulations with experiments.","authors":"Michael Schatz, Matthias Streun, Sven Jovanovic, Rüdiger-A Eichel, Josef Granwehr","doi":"10.5194/mr-5-167-2024","DOIUrl":"10.5194/mr-5-167-2024","url":null,"abstract":"<p><p>Combining electrochemistry (EC) and nuclear magnetic resonance (NMR) techniques has evolved from a challenging concept to an adaptable and versatile method for battery and electrolysis research. Continuous advancements in NMR hardware have fostered improved homogeneity of the static magnetic field, <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> , and the radio frequency field, <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> , yet fundamental challenges caused by introducing essential conductive components into the NMR sensitive volume remain. Cell designs in EC-NMR have largely been improved empirically, at times supported by magnetic field simulations. To propel systematic improvements of cell concepts, a workflow for a qualitative and semi-quantitative description of both <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> and <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> distortions is provided in this study. Three-dimensional finite element method (FEM) simulations of both <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> and <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> fields were employed to investigate cell structures with electrodes oriented perpendicular to <math> <mrow><msub><mi>B</mi> <mn>0</mn></msub> </mrow> </math> , which allow realistic EC-NMR measurements for battery and electrolysis applications. Particular attention is paid to field distributions in the immediate vicinity of electrodes, which is of prime interest for electrochemical processes. Using a cell with a small void outside the electrochemical active region, the relevance of design details and bubble formation is demonstrated. Moreover, <math> <mrow><msub><mi>B</mi> <mn>1</mn></msub> </mrow> </math> amplifications in coin cells provide an explanation for unexpectedly high sensitivity in previous EC-NMR studies, implying the potential for selective excitation of spins close to electrode surfaces. The correlation of this amplification effect with coin geometry is described by empirical expressions. The simulations were validated experimentally utilising frequency-encoded <sup>1</sup>H profile imaging and chemical shift imaging of <sup>1</sup>H, <sup>13</sup>C, and <sup>23</sup>Na resonances of <math> <mrow><msub><mi>NaHCO</mi> <mn>3</mn></msub> </mrow> </math> electrolyte. Finally, the theoretical and experimental results are distilled into design guidelines for EC-NMR cells.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"167-180"},"PeriodicalIF":0.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12178131/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Low-power WALTZ decoupling under magic-angle spinning NMR.","authors":"Luzian Thomas, Matthias Ernst","doi":"10.5194/mr-5-153-2024","DOIUrl":"10.5194/mr-5-153-2024","url":null,"abstract":"<p><p>Heteronuclear low-power decoupling using the solution-state wideband alternating-phase low-power technique for zero-residual splitting (WALTZ) sequences has become quite popular in solid-state protein NMR and seems to work well. However, there are no systematic studies that characterize these sequences under magic-angle spinning (MAS) and give recommendations on which parameter should be used. We have studied in detail the use of WALTZ-16 and WALTZ-64 as low-power decoupling sequences under 100 kHz MAS by characterizing the resonance conditions analytically using numerical simulations and experiments on model substances. The recoupling heteronuclear resonance conditions between the modulation frequency of the sequences and the MAS frequency is the most important feature. Pulse lengths corresponding to areas with vanishing first-order heteronuclear recoupling are good candidates for efficient decoupling. We have characterized two such conditions which can be defined using the nutation frequency of the radio frequency (RF) field ( <math> <mrow><msub><mi>ν</mi> <mn>1</mn></msub> </mrow> </math> ) and the spinning frequency ( <math> <mrow><msub><mi>ν</mi> <mi>r</mi></msub> </mrow> </math> ) by <math> <mrow><msub><mi>ν</mi> <mn>1</mn></msub> <mo>=</mo> <msub><mi>ν</mi> <mi>r</mi></msub> <mo>/</mo> <mn>10</mn></mrow> </math> and <math> <mrow><msub><mi>ν</mi> <mn>1</mn></msub> <mo>=</mo> <mn>2</mn> <msub><mi>ν</mi> <mi>r</mi></msub> <mo>/</mo> <mn>5</mn></mrow> </math> , which both lead to narrow lines and are stable against RF-field variations and chemical-shift offsets. More such conditions might exist but were not investigated here.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"153-166"},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12178133/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jörg Wolfgang Anselm Fischer, Julian Stropp, René Tschaggelar, Oliver Oberhänsli, Nicholas Alaniva, Mariko Inoue, Kazushi Mashima, Alexander Benjamin Barnes, Gunnar Jeschke, Daniel Klose
{"title":"Design and performance of an oversized-sample 35 GHz EPR resonator with an elevated <i>Q</i> value.","authors":"Jörg Wolfgang Anselm Fischer, Julian Stropp, René Tschaggelar, Oliver Oberhänsli, Nicholas Alaniva, Mariko Inoue, Kazushi Mashima, Alexander Benjamin Barnes, Gunnar Jeschke, Daniel Klose","doi":"10.5194/mr-5-143-2024","DOIUrl":"10.5194/mr-5-143-2024","url":null,"abstract":"<p><p>Continuous-wave electron paramagnetic resonance (EPR) spectroscopy at 35 GHz is an essential cornerstone in multi-frequency EPR studies and is crucial for differentiating multiple species in complex systems due to the improved <math><mi>g</mi></math> -tensor resolution compared to lower microwave frequencies. Especially for unstable and highly sensitive paramagnetic centers, the reliability of the measurements can be improved upon through the use of a single sample for EPR experiments at all frequencies. Besides the advantages, the lack of common availability of oversized-sample resonators at 35 GHz often limits scientists to lower frequencies or smaller sample geometries, and the latter may be non-trivial for sensitive materials. In this work, we present the design and performance of an oversized-sample 35 GHz EPR resonator with a high loaded <math><mi>Q</mi></math> value, <math> <mrow><msub><mi>Q</mi> <mi>L</mi></msub> </mrow> </math> , of up to 2550, well-suited for continuous-wave EPR and pulsed single-microwave-frequency experiments. The design is driven by electromagnetic field simulations, and the microwave characteristics of manufactured prototypes were found to be in agreement with the predictions. The resonator is based on a cylindrical cavity with a TE <math><msub><mi></mi> <mn>011</mn></msub> </math> mode, allowing for 3 mm sample access. The design targets that we met include high sensitivity, robustness, and ease of manufacturing and maintenance. The resonator is compatible with commercial EPR spectrometers and with helium flow, as well as with cryogen-free cryostats, allowing for measurements at temperatures down to 1.8 K. To highlight the general applicability, the resonator was tested on metal centers, as well as on organic radicals featuring extremely narrow lines.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"143-152"},"PeriodicalIF":0.0,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12178130/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PRESERVE: adding variable flip-angle excitation to transverse relaxation-optimized NMR spectroscopy.","authors":"Bernhard Brutscher","doi":"10.5194/mr-5-131-2024","DOIUrl":"10.5194/mr-5-131-2024","url":null,"abstract":"<p><p>We introduce the \"Polarization Restoring Excitation SEquence foR Versatile Experiments\" (PRESERVE) pulse sequence element, allowing variable flip-angle adjustment in 2D <math><msup><mi></mi> <mn>1</mn></msup> </math> H- <math><msup><mi></mi> <mn>15</mn></msup> </math> N and <math><msup><mi></mi> <mn>1</mn></msup> </math> H- <math><msup><mi></mi> <mn>13</mn></msup> </math> C transverse-relaxation-optimized-spectroscopy (TROSY)-type correlation experiments. PRESERVE-TROSY exploits a remarkable array of up to nine orthogonal coherence-transfer pathways, showcasing the remarkable potential of spin manipulations achievable through the design and optimization of nuclear magnetic resonance (NMR) pulse sequences.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"131-142"},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12178132/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Harry Harbor-Collins, Mohamed Sabba, Markus Leutzsch, Malcolm H Levitt
{"title":"<sup>1</sup>H-enhanced <sup>103</sup>Rh NMR spectroscopy and relaxometry of <sup>103</sup>Rh(acac)<sub>3</sub> in solution.","authors":"Harry Harbor-Collins, Mohamed Sabba, Markus Leutzsch, Malcolm H Levitt","doi":"10.5194/mr-5-121-2024","DOIUrl":"10.5194/mr-5-121-2024","url":null,"abstract":"<p><p>Recently developed polarisation transfer techniques are applied to the <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> nuclear magnetic resonance (NMR) of the <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi> <mo>(</mo> <mi>acac</mi> <msub><mo>)</mo> <mn>3</mn></msub> </mrow> </math> coordination complex in solution. Four-bond <math> <mrow><msup><mi></mi> <mn>1</mn></msup> <mi>H</mi></mrow> </math> - <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> <math><mi>J</mi></math> couplings of around 0.39 <math><mrow><mi>Hz</mi></mrow> </math> are exploited to enhance the <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> NMR signal and to estimate the <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> and <math> <mrow><msub><mi>T</mi> <mn>2</mn></msub> </mrow> </math> relaxation times as a function of field and temperature. The <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> longitudinal <math> <mrow><msub><mi>T</mi> <mn>1</mn></msub> </mrow> </math> relaxation in <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi> <mo>(</mo> <mi>acac</mi> <msub><mo>)</mo> <mn>3</mn></msub> </mrow> </math> is shown to be dominated by the spin-rotation mechanism, with an additional field-dependent contribution from the <math> <mrow><msup><mi></mi> <mn>103</mn></msup> <mi>Rh</mi></mrow> </math> chemical shift anisotropy.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"121-129"},"PeriodicalIF":0.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12163919/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144303850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis of chi angle distributions in free amino acids via multiplet fitting of proton scalar couplings.","authors":"Nabiha R Syed, Nafisa B Masud, Colin A Smith","doi":"10.5194/mr-5-103-2024","DOIUrl":"10.5194/mr-5-103-2024","url":null,"abstract":"<p><p>Scalar couplings are a fundamental aspect of nuclear magnetic resonance (NMR) experiments and provide rich information about electron-mediated interactions between nuclei. <sup>3</sup> <math><mrow><mi>J</mi></mrow> </math> couplings are particularly useful for determining molecular structure through the Karplus relationship, a mathematical formula used for calculating <sup>3</sup> <math><mrow><mi>J</mi></mrow> </math> coupling constants from dihedral angles. In small molecules, scalar couplings are often determined through analysis of one-dimensional proton spectra. Larger proteins have typically required specialized multidimensional pulse programs designed to overcome spectral crowding and multiplet complexity. Here, we present a generalized framework for fitting scalar couplings with arbitrarily complex multiplet patterns using a weak-coupling model. The method is implemented in FitNMR and applicable to one-dimensional, two-dimensional, and three-dimensional NMR spectra. To gain insight into the proton-proton coupling patterns present in protein side chains, we analyze a set of free amino acid one-dimensional spectra. We show that the weak-coupling assumption is largely sufficient for fitting the majority of resonances, although there are notable exceptions. To enable structural interpretation of all couplings, we extend generalized and self-consistent Karplus equation parameterizations to all <math><mi>χ</mi></math> angles. An enhanced model of side-chain motion incorporating rotamer statistics from the Protein Data Bank (PDB) is developed. Even without stereospecific assignments of the beta hydrogens, we find that two couplings are sufficient to exclude a single-rotamer model for all amino acids except proline. While most free amino acids show rotameric populations consistent with crystal structure statistics, beta-branched valine and isoleucine deviate substantially.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 2","pages":"103-120"},"PeriodicalIF":0.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11570886/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Charles-E Dutoit, Hania Ahouari, Quentin Denoyelle, Simon Pondaven, Hervé Vezin
{"title":"Second-harmonic electron paramagnetic resonance spectroscopy and imaging reveal metallic lithium depositions in Li-ion batteries.","authors":"Charles-E Dutoit, Hania Ahouari, Quentin Denoyelle, Simon Pondaven, Hervé Vezin","doi":"10.5194/mr-5-87-2024","DOIUrl":"10.5194/mr-5-87-2024","url":null,"abstract":"<p><p>We have investigated metallic lithium particle nucleation following lithiation and delithiation steps of the graphite electrode using X-band electron paramagnetic resonance (EPR). Metallic lithium aggregates like dendrites and/or filaments which are formed during electrochemical cycling on the graphite anode are complex structures which may lead to internal short-circuit and safety issues. Understanding and following, in real conditions, this nucleation process is necessary to improve the development of Li-ion batteries. The complexity to detect metallic lithium structures inside Li-ion batteries depends on the number of EPR lines and their linewidth. The presence of lithiated graphite phases affects the detection of micrometric Li-metal elements. Herein, we report a new approach using cw-EPR (continuous-wave EPR) spectroscopy and imaging, combining the first- and second-harmonic detection schemes to provide evidence for the metallic lithium aggregate nucleation in these negative electrodes. Although the first harmonic gives all the EPR signals present in the sample, it is found that the second-harmonic EPR signal is mainly sensitive to metallic lithium depositions.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"5 1","pages":"87-93"},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12082685/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144096209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Various facets of intermolecular transfer of phase coherence by nuclear dipolar fields.","authors":"Philippe Pelupessy","doi":"10.5194/mr-4-271-2023","DOIUrl":"10.5194/mr-4-271-2023","url":null,"abstract":"<p><p>It has long been recognized that dipolar fields can mediate intermolecular transfer of phase coherence from abundant solvent to sparse solute spins. Generally, the dipolar field has been considered while acting during prolonged free-precession delays. Recently, we have shown that transfer can also occur during suitable uninterrupted radio frequency pulse trains that are used for total correlation spectroscopy. Here, we will expand upon the latter work. First, analytical expressions for the evolution of the solvent magnetization under continuous irradiation and the influence of the dipolar field are derived. These expressions facilitate the simulations of the transfer process. Then, a pulse sequence for the retrieval of high-resolution spectra in inhomogeneous magnetic fields is described, along with another sequence to detect a transfer from an intermolecular double-quantum coherence. Finally, various schemes are discussed where the magnetization is modulated by a combination of multiple selective radio frequency pulses and pulsed field gradients in different directions. In these schemes, the magnetization is manipulated in such a way that the dipolar field, which originates from a single-spin species, can be decomposed into two components. Each component originates from a part of the magnetization that is modulated in a different direction. Both can independently, but simultaneously, mediate an intermolecular transfer of phase coherence.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"4 2","pages":"271-283"},"PeriodicalIF":0.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10776886/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139418709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The solid effect of dynamic nuclear polarization in liquids – accounting for <i>g</i>-tensor anisotropy at high magnetic fields","authors":"Deniz Sezer, Danhua Dai, Thomas F. Prisner","doi":"10.5194/mr-4-243-2023","DOIUrl":"https://doi.org/10.5194/mr-4-243-2023","url":null,"abstract":"Abstract. In spite of its name, the solid effect of dynamic nuclear polarization (DNP) is also operative in viscous liquids, where the dipolar interaction between the polarized nuclear spins and the polarizing electrons is not completely averaged out by molecular diffusion on the timescale of the electronic spin–spin relaxation time. Under such slow-motional conditions, it is likely that the tumbling of the polarizing agent is similarly too slow to efficiently average the anisotropies of its magnetic tensors on the timescale of the electronic T2. Here we extend our previous analysis of the solid effect in liquids to account for the effect of g-tensor anisotropy at high magnetic fields. Building directly on the mathematical treatment of slow tumbling in electron spin resonance (Freed et al., 1971), we calculate solid-effect DNP enhancements in the presence of both translational diffusion of the liquid molecules and rotational diffusion of the polarizing agent. To illustrate the formalism, we analyze high-field (9.4 T) DNP enhancement profiles from nitroxide-labeled lipids in fluid lipid bilayers. By properly accounting for power broadening and motional broadening, we successfully decompose the measured DNP enhancements into their separate contributions from the solid and Overhauser effects.","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135271885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lauren E Price, Nicholas Alaniva, Marthe Millen, Till Epprecht, Michael Urban, Alexander Däpp, Alexander B Barnes
{"title":"Cryogenic-compatible spherical rotors and stators for magic angle spinning dynamic nuclear polarization.","authors":"Lauren E Price, Nicholas Alaniva, Marthe Millen, Till Epprecht, Michael Urban, Alexander Däpp, Alexander B Barnes","doi":"10.5194/mr-4-231-2023","DOIUrl":"10.5194/mr-4-231-2023","url":null,"abstract":"<p><p>Cryogenic magic angle spinning (MAS) is a standard technique utilized for dynamic nuclear polarization (DNP) in solid-state nuclear magnetic resonance (NMR). Here we describe the optimization and implementation of a stator for cryogenic MAS with 9.5 mm diameter spherical rotors, allowing for DNP experiments on large sample volumes. Designs of the stator and rotor for cryogenic MAS build on recent advancements of MAS spheres and take a step further to incorporate sample insert and eject and a temperature-independent spinning stability of <math><mrow><mo>±</mo><mn>1</mn></mrow></math> Hz. At a field of 7 T and spinning at 2.0 kHz with a sample temperature of 105-107 K, DNP enhancements of 256 and 200 were observed for 124 and 223 <math><mrow><mi>µ</mi></mrow></math>L sample volumes, respectively, each consisting of 4 M <math><msup><mi></mi><mn>13</mn></msup></math>C, <math><msup><mi></mi><mn>15</mn></msup></math>N-labeled urea and 20 mM AMUPol in a glycerol-water glassy matrix.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":"231-241"},"PeriodicalIF":0.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539783/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48204277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}