Magnetic resonance (Gottingen, Germany)最新文献

{"title":"Coherence locking in a parallel nuclear magnetic resonance probe defends against gradient field spillover.","authors":"Mengjia He, Neil MacKinnon, Dominique Buyens, Burkhard Luy, Jan G Korvink","doi":"10.5194/mr-6-173-2025","DOIUrl":"10.5194/mr-6-173-2025","url":null,"abstract":"<p><p>The implementation of parallel nuclear magnetic resonance detection aims to enhance measurement throughput in support of high-throughput-screening applications, including, for example, drug discovery. In support of modern pulse sequences and solvent suppression methods, each detection site must have independent pulsed field gradient capabilities. Hereby, a challenge is introduced in which the local gradients applied in parallel detectors introduce field spillover into adjacent channels, leading to spin dephasing and, hence, to signal suppression. This study proposes a compensation scheme employing optimized pulses to achieve coherence locking during gradient pulse periods. The design of coherence-locking pulses utilizes optimal control to address gradient-induced field inhomogeneity. These pulses are applied in a pulsed-gradient spin echo (PGSE) experiment and a parallel heteronuclear single quantum coherence (HSQC) experiment, demonstrating their effectiveness in protecting the desired coherences from gradient field spillover. This compensation scheme presents a valuable solution for magnetic resonance probes equipped with parallel and independently switchable gradient coils.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"173-181"},"PeriodicalIF":0.0,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12302023/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144736011","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":"Automated wide-line nuclear quadrupole resonance of mixed-cation lead-halide perovskites.","authors":"Jop W Wolffs, Jennifer S Gómez, Gerrit E Janssen, Gilles A de Wijs, Arno P M Kentgens","doi":"10.5194/mr-6-143-2025","DOIUrl":"10.5194/mr-6-143-2025","url":null,"abstract":"<p><p>Nuclear quadrupole resonance (NQR), a technique related to nuclear magnetic resonance, is extremely sensitive to local crystal composition and structure. Unfortunately, in disordered materials, this sensitivity also leads to very large linewidths, presenting a technical challenge and requiring a serious time investment to get a full spectrum. Here, we describe our newly developed, automated NQR set-up to acquire high-quality wide-line spectra. Using this set-up, we carried out ¹²⁷I NQR on three mixed-cation lead-halide perovskites (LHPs) of the form MA _<i>x</i> FA_1-<i>x</i> PbI₃ (where MA denotes methylammonium; FA denotes formamidinium; and <math><mrow><mi>x</mi> <mspace></mspace> <mo>=</mo></mrow> </math> 0.25, 0.50 and 0.75) at various temperatures. We achieve a signal-to-noise ratio of up to <math><mrow><mo>∼</mo> <mspace></mspace> <mn>400</mn></mrow> </math> for lineshapes with a full width at half maximum of <math><mrow><mo>∼</mo> <mspace></mspace> <mn>2.5</mn> <mspace></mspace> <mi>MHz</mi></mrow> </math> acquired with a spectral width of 20 MHz in the course of 2-3 d. The spectra, which at least partially exhibit features encoding structural information, are interpreted using a statistical model. This model finds a degree of MA-MA and FA-FA clustering ( <math><mrow><mn>0.2</mn> <mspace></mspace> <mo>≤</mo> <mspace></mspace> <mi>S</mi> <mspace></mspace> <mo>≤</mo> <mspace></mspace> <mn>0.35</mn></mrow> </math> ). This proof-of-principle for both the wide-line NQR set-up and the statistical model widens the applicability of an underutilised avenue of non-invasive structural research.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"143-155"},"PeriodicalIF":0.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12285786/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144700596","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":"3D-printed microcell for protein NMR at high ionic strengths and small sample volumes.","authors":"Tayeb Kakeshpour, Martin D Gelenter, Jinfa Ying, Ad Bax","doi":"10.5194/mr-6-157-2025","DOIUrl":"10.5194/mr-6-157-2025","url":null,"abstract":"<p><p>Standard solution NMR measurements use 5 mm outer diameter (OD) sample tubes that require ca. 0.5 mL of solvent to minimize \"end effects\" on magnetic field homogeneity in the active volume of the sample. Shigemi cells reduce the solvent requirement to ca. 0.29 mL. At high ionic strength or at ultrahigh magnetic fields, smaller OD samples are needed to study samples in conductive, radiofrequency-absorbing solvents such as water. We demonstrate an effective and inexpensive alternative for reducing the active sample volume to 0.13 mL by 3D printing ellipsoidal shaped cells that are inserted into 5 mm OD NMR tubes. Static magnetic susceptibility, <math><mi>χ</mi></math> , of printer resin was measured using a simple slice-selection pulse sequence. We found that the <math><mi>χ</mi></math> of water increases linearly with NaCl concentration from <math><mrow><mo>-</mo> <mn>9.05</mn></mrow> </math> to <math><mrow><mo>-</mo> <mn>8.65</mn></mrow> </math> ppm for 0 to 2 M NaCl. The <math><mi>χ</mi></math> of D₂O was measured to be <math><mrow><mo>-</mo> <mn>9.01</mn></mrow> </math> ppm. The susceptibility difference between the resin ( <math><mrow><mi>χ</mi> <mo>=</mo> <mo>-</mo> <mn>9.40</mn></mrow> </math> ppm) and water can be minimized by paramagnetic doping of the resin. Such doping was found to be unnecessary for obtaining high-quality protein NMR spectra when using ellipsoidal-shaped cells that are insensitive to susceptibility mismatching. The microcells offer outstanding radiofrequency (RF) and good <math> <mrow><msub><mi>B</mi> <mi>o</mi></msub> </mrow> </math> homogeneities. Integrated 600 MHz heteronuclear single quantum coherence (HSQC) signal intensities for the microcell sample in phosphate-buffered saline (PBS) buffer were <math><mrow><mn>6.5</mn> <mo>±</mo> <mn>4</mn></mrow> </math> % lower than for 0.5 mL of the same protein solution in a regular 5 mm sample tube. The cell is demonstrated for N-acetylated <math><mi>α</mi></math> -synuclein in PBS buffer and for observing tetramerization of melittin at 2 M NaCl.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"157-172"},"PeriodicalIF":0.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12296210/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144736010","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":"Inter-residue through-space scalar ¹⁹F-¹⁹F couplings between CH₂F groups in a protein.","authors":"Yi Jiun Tan, Elwy H Abdelkader, Iresha D Herath, Ansis Maleckis, Gottfried Otting","doi":"10.5194/mr-6-131-2025","DOIUrl":"10.5194/mr-6-131-2025","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Using cell-free protein synthesis, the protein G B1 domain (GB1) was prepared with uniform high-level substitution of leucine by (2 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; ,4 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; )-5-fluoroleucine (FLeu1), (2 &lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt; ,4 &lt;math&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/math&gt; )-5-fluoroleucine (FLeu2), or 5,5&lt;sup&gt;'&lt;/sup&gt;-difluoroleucine (diFLeu). &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; nuclear magnetic resonance (NMR) spectra showed chemical shift ranges spanning more than 9 &lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ppm&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; . Through-space scalar &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt; &lt;msup&gt;&lt;mtext&gt;-&lt;/mtext&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; couplings between &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups arising from transient fluorine-fluorine contacts are readily manifested in [ &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; , &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; ]-TOCSY spectra. The &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; chemical shifts correlate with the three-bond &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; - &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; couplings ( &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; ), confirming the &lt;math&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/math&gt; -gauche effect as the predominant determinant of the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; chemical shifts of the &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups. Different &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; couplings of different &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups indicate that the rotation of the &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups can be sufficiently restricted in different protein environments to result in the preferential population of a single rotamer. The &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;J&lt;/mi&gt; &lt;mi&gt;HF&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;/math&gt; couplings also show that &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups populate the different rotameric states differently in the 5,5&lt;sup&gt;'&lt;/sup&gt;-difluoroleucine residues than in the monofluoroleucine analogues, showing that two &lt;math&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;CH&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; groups in close proximity influence each other's conformation. Nonetheless, the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt; &lt;mn&gt;19&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; resonances of the &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;C&lt;/mi&gt; &lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt; &lt;/math&gt; and &lt;math&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;C&lt;/mi&gt; &lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 2","pages":"131-142"},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12281167/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144700597","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":"Pseudo rotary resonance relaxation dispersion effects in isotropic samples.","authors":"Evgeny Nimerovsky, Jonas Mehrens, Loren B Andreas","doi":"10.5194/mr-6-119-2025","DOIUrl":"10.5194/mr-6-119-2025","url":null,"abstract":"<p><p>Enhanced transverse relaxation near rotary resonance conditions is a well-documented effect for anisotropic solid samples undergoing magic-angle spinning (MAS). We report transverse signal decay associated with rotary resonance conditions for rotating liquids, a surprising observation, since first-order anisotropic interactions are averaged at a much faster timescale compared with the spinning frequency. We report measurements of <math> <mrow><msup><mi></mi> <mn>13</mn></msup> <mi>C</mi></mrow> </math> and <math> <mrow><msup><mi></mi> <mn>1</mn></msup> <mi>H</mi></mrow> </math> signal intensities under spin lock for spinning samples of polybutadiene rubber, polyethylene glycol solution, and 99.96 % <math> <mrow><msub><mi>D</mi> <mn>2</mn></msub> <mi>O</mi></mrow> </math> . A drastic reduction in spin-lock signal intensities is observed when the spin-lock frequency matches 1 or 2 times the MAS rate. In addition, oscillations of the signal are observed, consistent with a coherent origin of the effect, a pseudo rotary resonance relaxation dispersion (pseudo-RRD). Through simulations, we qualitatively describe the appearance of pseudo-RRD, which can be explained by time dependence caused by sample rotation and an inhomogeneous field, the origin of which is an instrumental imperfection. Consideration of this effect is important for MAS experiments based on rotary resonance conditions and motivates the design of new MAS coils with improved radio frequency (RF)-field homogeneity.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"119-129"},"PeriodicalIF":0.0,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247080/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628062","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":"ih-RIDME: a pulse EPR experiment to probe the heterogeneous nuclear environment.","authors":"Sergei Kuzin, Victoriya N Syryamina, Mian Qi, Moritz Fischer, Miriam Hülsmann, Adelheid Godt, Gunnar Jeschke, Maxim Yulikov","doi":"10.5194/mr-6-93-2025","DOIUrl":"10.5194/mr-6-93-2025","url":null,"abstract":"<p><p>The intermolecular hyperfine relaxation-induced dipolar modulation enhancement experiment (ih-RIDME) is a pulse electron paramagnetic resonance (EPR) experiment that can be used to probe the properties of a nuclear spin bath in the vicinity of an unpaired electron. The underlying mechanism is the hyperfine spectral diffusion of the electron spin during the mixing block. A quantitative description of the diffusion kinetics being applied to establish the ih-RIDME data model allows one to extend this method to systems with heterogeneous nuclear arrangements assuming a distribution of the local nuclear densities. The heterogeneity can stem from the solvent or the intrinsic nuclei of a structurally flexible (macro)molecule. Therefore, the fitted distribution function can further serve as a method for heterogeneity characterization, quantification and structure-based analysis. Here, we present a detailed introduction to the principles of ih-RIDME application to heterogeneous systems. We discuss the spectral resolution, determination of the spectral diffusion parameters and influence of noise in the experimental data. We further demonstrate the application of the ih-RIDME method to a model spin-labelled macromolecule with unstructured domains. The fitted distribution of local proton densities was reproduced with the help of a conformational ensemble generated using the Monte Carlo approach. Finally, we discuss several pulse sequences exploiting the HYperfine Spectral Diffusion Echo MOdulatioN (HYSDEMON) effect with an improved signal-to-noise ratio.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"93-112"},"PeriodicalIF":0.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247092/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628060","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":"Analytical expressions for the time evolution of spin systems affected by two or more interactions.","authors":"Günter Hempel","doi":"10.5194/mr-6-77-2025","DOIUrl":"10.5194/mr-6-77-2025","url":null,"abstract":"<p><p>Analytical expressions for the description of the time evolution of spin systems beyond product-operator formalism (POF) can be obtained if a low-dimensional subspace of the Liouville space has been found in which the time evolution of the spin system takes place completely. This can be achieved using a procedure that consists of repeated application of the commutator of the Hamiltonian with the density operator. This iteration continues as long as the result of such a commutator operation contains a term that is linearly independent of all the operators appearing in the previous commutator operations. The coefficients of the resulting system of commutator relations can be immediately inserted into the generic propagation formulae given in this article if the system contains two, three, or four equations. In cases where the validity conditions of any of these propagation formulae are not met, the coefficients are used as intermediate steps to obtain both the Liouvillian and propagator matrices of the system. Several application examples are given where an analytical equation can be obtained for the description of the time evolution of small spin systems under the influence of two or more interactions. This procedure for finding the Liouvillian matrix is not limited to time-independent interactions. Some examples illustrate the treatment of time-dependent problems using this method.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"77-92"},"PeriodicalIF":0.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247082/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628058","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":"Increased sensitivity in electron-nuclear double resonance spectroscopy with chirped radiofrequency pulses.","authors":"Julian Stropp, Nino Wili, Niels C Nielsen, Daniel Klose","doi":"10.5194/mr-6-33-2025","DOIUrl":"10.5194/mr-6-33-2025","url":null,"abstract":"<p><p>Electron-nuclear double resonance (ENDOR) spectroscopy is an EPR technique to detect the nuclear frequency spectra of hyperfine coupled nuclei close to paramagnetic centers, which have interactions that are not resolved in continuous wave EPR spectra and may be fast relaxing on the timescale of NMR. For the common case of non-crystalline solids, such as powders or frozen solutions of transition metal complexes, the anisotropy of the hyperfine and nuclear quadrupole interactions renders ENDOR lines often several megahertz (MHz) broad, thus diminishing intensity. With commonly used ENDOR pulse sequences, only a small fraction of the NMR/ENDOR line is excited with a typical radiofrequency (RF) pulse length of several tens of microseconds ( <math><mrow><mi>µ</mi></mrow> </math> s), and this limits the sensitivity in conventional ENDOR experiments. In this work, we show the benefit of chirped RF excitation in frequency-domain ENDOR as a simple yet effective way to significantly improve sensitivity. We demonstrate on a frozen solution of Cu(II)-tetraphenylporphyrin that the intensity of broad copper and nitrogen ENDOR lines increases up to 9-fold compared to single-frequency RF excitation, thus making the detection of metal ENDOR spectra more feasible. The tunable bandwidth of the chirp RF pulses allows the operator to optimize for sensitivity and choose a tradeoff with resolution, opening up options previously inaccessible in ENDOR spectroscopy. Also, chirp pulses help to reduce RF amplifier overtones, since lower RF powers suffice to achieve intensities matching conventional ENDOR. In 2D triple resonance experiments (TRIPLE), the signal increase exceeds 10 times for some lines, thus making chirped 2D TRIPLE experiments feasible even for broad peaks in manageable acquisition times.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"33-42"},"PeriodicalIF":0.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247087/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628061","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":"Electron-spin decoherence in trityl radicals in the absence and presence of microwave irradiation.","authors":"Gunnar Jeschke, Nino Wili, Yufei Wu, Sergei Kuzin, Hugo Karas, Henrik Hintz, Adelheid Godt","doi":"10.5194/mr-6-15-2025","DOIUrl":"10.5194/mr-6-15-2025","url":null,"abstract":"<p><p>Trityl radicals feature prominently as polarizing agents in solid-state dynamic nuclear polarization experiments and as spin labels in distance distribution measurements by pulsed dipolar EPR spectroscopy techniques. Electron-spin coherence lifetime is a main determinant of performance in these applications. We show that protons in these radicals contribute substantially to decoherence, although the radicals were designed with the aim of reducing proton hyperfine interaction. By spin dynamics simulations, we can trace back the nearly complete Hahn echo decay for a Finland trityl radical variant within 7 <math><mrow><mi>µ</mi></mrow> </math> s to the contribution from tunnelling of the 36 methyl protons in the radical core. This contribution, as well as the contribution of methylene protons in OX063 and OX071 trityl radicals, to Hahn echo decay can be predicted rather well by the previously introduced analytical pair product approximation. In contrast, predicting decoherence of electron spins dressed by a microwave field proves to be a hard problem where correlations between more than two protons contribute substantially. Cluster correlation expansion (CCE) becomes borderline numerically unstable already at order 3 at times comparable to the decoherence time <math> <mrow><msub><mi>T</mi> <mrow><mn>2</mn> <mi>ρ</mi></mrow> </msub> </mrow> </math> and cannot be applied at order 4. We introduce partial CCE that alleviates this problem and reduces computational effort at the expense of treating only part of the correlations at a particular order. Nevertheless, dressed-spin decoherence simulations for systems with more than 100 protons remain out of reach, whereas they provide only semi-quantitative predictions for 24 to 48 protons. Our experimental and simulation results indicate that solid-state magnetic resonance experiments with trityl radicals will profit from perdeuteration of the compounds.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"6 1","pages":"15-32"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12247090/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144628059","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":"Workflow for systematic design of electrochemical in operando NMR cells by matching <i>B</i> ₀ and <i>B</i> ₁ 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 ¹H profile imaging and chemical shift imaging of ¹H, ¹³C, and ²³Na 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}