Journal of Magnetic Resonance, Series A最新文献_第9页

Easily Tunable Crossed-Loop (Bimodal) EPR Resonator 容易调谐的交叉回路(双峰)EPR谐振器

Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0173

George A. Rinard, Richard W. Quine, Barnard T. Ghim, Sandra S. Eaton, Gareth R. Eaton

{"title":"Easily Tunable Crossed-Loop (Bimodal) EPR Resonator","authors":"George A. Rinard, Richard W. Quine, Barnard T. Ghim, Sandra S. Eaton, Gareth R. Eaton","doi":"10.1006/jmra.1996.0173","DOIUrl":"10.1006/jmra.1996.0173","url":null,"abstract":"<div>A new crossed-loop resonator (CLR) structure is described that uses two orthogonal resonators to isolate the EPR signal from the microwave source. Resonators of this type are usually referred to as bimodal, which is descriptive of cavity or distributed element resonators. However, it is more useful to think of the new resonator as two virtually independent lumped-element resonators that have a common sample volume where the loops of the two resonators meet orthogonally. The first resonator excites the spins, and the second resonator (or resonant section of the CLR) acts like an antenna that detects only the signal caused by the spin system. In this manner, the very phenomenom that is being studied is used to separate the desired EPR signal from the microwave source and performs the function of the circulator. The signal coupled into the second resonator is due to the spin system. The phase noise of the source is reflected from the first resonator back toward the source and is efficiently isolated from the second resonator and the EPR signal. This resonator structure eliminates the need for the circulator, simplifies the spectrometer circuit, virtually eliminates source phase noise in the detected signal, and allows dispersion spectra to be measured with the same high signal-to-noise (S/N) as absorption spectra. In addition, for pulse experiments, this resonator greatly decreases the dead time of the instrument and allows measurement of a portion of the signal previously inaccessible with other resonators. The CLR is rugged, easy to tune, does not have to be critically coupled, and is easily adjusted to maintain source isolation when the sample is changed.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 50-57"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79937980","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}

引用次数: 51

A Double-Quantum119Sn Rotational-Resonance Study 双量子119sn旋转共振研究

Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0181

Robin Challoner, Angelika Sebald

引用次数: 6

Quantitative Analysis of EPR Spectra of Powdered Samples Containing a Mixture of Various Paramagnetic Particles 含有各种顺磁颗粒混合物的粉末样品的EPR光谱定量分析

Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0169

P. Pelikán , M. Liška , M. Valko , M. Mazúr

引用次数: 20

15N NMR Spectroscopy of Cyclotriphosphazenes and Polyphosphazenes Based on31P,15N HMQC Correlations 基于31p,15N HMQC相关性的环三磷腈和聚磷腈的15N核磁共振波谱

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0155

Elvira Peláez-Arango, Francisco J. Garcı́a-Alonso, Gabino Carriedo, Fernando López-Ortiz

{"title":"15N NMR Spectroscopy of Cyclotriphosphazenes and Polyphosphazenes Based on31P,15N HMQC Correlations","authors":"Elvira Peláez-Arango, Francisco J. Garcı́a-Alonso, Gabino Carriedo, Fernando López-Ortiz","doi":"10.1006/jmra.1996.0155","DOIUrl":"10.1006/jmra.1996.0155","url":null,"abstract":"<div>A31P and15N NMR study of cyclotriphosphazenes 1–4 and polyphosphazene 5 has been carried out including solvent and substituent effects.15N chemical shifts and31P,15N coupling constants are readily obtained through 1D and 2D31P,15N HMQC correlation spectroscopy on natural-abundance samples. This methodology combined with spectral simulation also yields15N-induced isotope shifts.31P and15N are both relatively insensitive to changes in solvent polarity. Chemical shifts are reasonably explained in terms of electronic density variations, and31P,15N couplings are rationalized by considering their absolute sign, which depends on the substituent bonded to phosphorus.15N proved to be more sensitive to structural modifications than31P. Therefore, the availability of15N NMR data on cyclotriphosphazenes can be considered a valuable tool in the design of model compounds for polyphosphazene synthesis.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"121 2","pages":"Pages 154-159"},"PeriodicalIF":0.0,"publicationDate":"1996-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0155","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73810913","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}

引用次数: 6

Multiple-Pulse Line Narrowing under Fast Magic-Angle Spinning 快速魔角纺丝下多脉冲线变窄

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0156

S. Hafner, H.W. Spiess

引用次数: 43

Measuring Diffusion in Liquids with a Single Gradient Pulse 用单梯度脉冲测量液体中的扩散

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0162

P. Robyr, R. Bowtell

引用次数: 26

Use of Autocorrelation-Like Function to Improve the Performance of Linear-Prediction Parameter Estimators 利用类自相关函数提高线性预测参数估计器的性能

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0148

M. Fedrigo, G. Esposito, S. Cattarinussi, P. Viglino, F. Fogolari

{"title":"Use of Autocorrelation-Like Function to Improve the Performance of Linear-Prediction Parameter Estimators","authors":"M. Fedrigo, G. Esposito, S. Cattarinussi, P. Viglino, F. Fogolari","doi":"10.1006/jmra.1996.0148","DOIUrl":"10.1006/jmra.1996.0148","url":null,"abstract":"<div>In this work, a novel approach to the usage of an autocorrelation function in order to improve signal-to-noise ratio (SNR) is presented. This method avoids the usual problems entailed by standard autocorrelation function-based approaches to nonstationary signals such as NMR signals. The Cadzow autocorrelation matrix approach to transient data is often not suitable for time-domain signal analysis; in fact, it does not maintain the Hankel structure of the prediction matrix, which is mandatory for many linear-prediction (LP) applications. The approach presented here conserves the Hankel structure of the prediction matrix and, moreover, does not change the frequency and linewidth parameters of the signal components. Furthermore, the proposed autocorrelation-like function permits a weighting of the individual components according to theirT2decay constant. This property opens new possibilities for retrieving signal parameters by LP procedures. These new procedures are applied to simulated 2D signals and 1D NMR measurements of phosphorus metabolites in frog muscle.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"121 2","pages":"Pages 97-107"},"PeriodicalIF":0.0,"publicationDate":"1996-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0148","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76849054","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}

引用次数: 4

Plane Selection in Indirect MARF Solid-State Imaging 间接MARF固态成像中的平面选择

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0150

F. De Luca, S. Motta, N. Lugeri, B. Maraviglia

引用次数: 5

Reduction of Sideband Intensities in Adiabatic Decoupling Using Modulation Generated through Adiabatic R-Variation (MGAR) 利用绝热r变(MGAR)调制降低绝热去耦中的边带强度

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0166

Tsang-Lin Hwang , Michael Garwood , Alberto Tannus , Peter C.M. van Zul

引用次数: 12

Effective Diffusion Times in Multiple-Pulse PFG Diffusion Measurements in Porous Media 多孔介质中多脉冲PFG扩散测量的有效扩散时间

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0159

E.J. Fordham , P.P. Mitra , L.L. Latour

引用次数: 30