Journal of Magnetic Resonance, Series A最新文献_第4页

Line Narrowing in Solid-State Proton NMR with Acquisition Delay 具有捕获延迟的固态质子核磁共振谱线变窄

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0213

B.M. Fung, Tat-Hung Tong, Thilo Dollase, Matthew L. Magnuson

{"title":"Line Narrowing in Solid-State Proton NMR with Acquisition Delay","authors":"B.M. Fung, Tat-Hung Tong, Thilo Dollase, Matthew L. Magnuson","doi":"10.1006/jmra.1996.0213","DOIUrl":"10.1006/jmra.1996.0213","url":null,"abstract":"<div>Organic solids have extensive proton–proton dipolar interactions, and their1H NMR linewidths are very large even with magic-angle spinning at moderate speeds. Recently it has been shown that substantial narrowing of the proton linewidths of organic solids can be achieved by using single-pulse excitation with acquisition delay or spin echo [S. Ding and C. A. McDowell,J. Magn. Reson. A111, 212 (1994); 115, 141 (1995); 117, 171 (1995)]. This interesting line-narrowing phenomenon has been further examined through the study of several amino acids, their deuterated analogs, and some aromatic compounds. The results confirm that narrow proton peaks are observed with long acquisition delay, and the peaks appear in the appropriate chemical-shift ranges for organic protons (0–10 ppm with respect to tetramethylsilane). However, except for some special cases, the observed peaks cannot be assigned to individual types of protons based on chemical-shift considerations only. To explore the reason for the line narrowing, the effect of acquisition delay on the19F linewidth of CaF2was also studied and compared with that on the1H linewidths of organic solids. It is suggested that the broad proton peak in an organic solid is a superposition of numerous transitions. These transitions have different linewidths, and the narrow peaks in the spectrum remain observable with long acquisition delays.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"123 1","pages":"Pages 56-63"},"PeriodicalIF":0.0,"publicationDate":"1996-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0213","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19941455","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: 9

Effect of Paramagnetic Ions on NMR Relaxation of Fluids at Solid Surfaces 顺磁离子对固体表面流体核磁共振弛豫的影响

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0218

I. Foley, S.A. Farooqui, R.L. Kleinberg

引用次数: 168

An Improved 2D Magic-Angle-Turning Pulse Sequence for the Measurement of Chemical-Shift Anisotropy 一种用于化学位移各向异性测量的改进二维魔角转向脉冲序列

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0227

Zhehong Gan, R.R. Ernst

引用次数: 25

High-Resolution NMR Measurement of Molecular Self-Diffusion by Fast Multi-Spin-Echo Diffusion Sequences 基于快速多自旋回波扩散序列的高分辨率核磁共振分子自扩散测量

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0223

S.Sendhil Velan, N. Chandrakumar

引用次数: 13

The Theory of ESR Hyperfine-Structure Narrowing as Applied to Wide-Gap Semimagnetic Semiconductors ESR超精细结构窄化理论在宽间隙半磁半导体中的应用

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0209

M.N. Aliev, L.R. Tagirov , V.S. Tagiev

引用次数: 4

Gradient-Selected NOESY—A Fourfold Reduction of the Measurement Time for the NOESY Experiment 梯度选择噪声-一种将噪声实验测量时间缩短四倍的方法

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0222

Ronald Wagner, Stefan Berger

引用次数: 164

Hahn Spin Echoes in Large Static Gradients Following a Series of 90° Pulses 大静态梯度下一系列90°脉冲的哈恩自旋回波

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0212

Alex D. Bain , E.W. Randall

{"title":"Hahn Spin Echoes in Large Static Gradients Following a Series of 90° Pulses","authors":"Alex D. Bain , E.W. Randall","doi":"10.1006/jmra.1996.0212","DOIUrl":"https://doi.org/10.1006/jmra.1996.0212","url":null,"abstract":"<div>The intensities of the Hahn spin echoes produced by a series of 90° pulses applied to a sample in large static field gradients are calculated. Static gradients are important because they can be very much larger than pulsed field gradients and echoes can be collected without recovery time problems. One application is for imaging using the stray field of a magnet (STRAFI). The high strength of the gradients in the stray field allows the imaging of solids and other systems with very broad lines. In an imaging pulse sequence consisting of pulses with phases 90°x—(90°y)n, the echoes (calculated in the absence of spin relaxation) have relative intensities of 1:[formula]:[formula]:1<math><mtext>1</mtext><mtext>8</mtext></math>:1<math><mtext>1</mtext><mtext>8</mtext></math>, etc., whereas a 90°x—(90°x)npulse sequence produces echoes which have relative intensities of 1:<math><mtext>1</mtext><mtext>2</mtext></math>:−<math><mtext>1</mtext><mtext>2</mtext></math>:−<math><mtext>3</mtext><mtext>8</mtext></math>:<math><mtext>3</mtext><mtext>8</mtext></math>, etc. A simple way of calculating these intensities is presented, using an irreducible tensor approach that has been termed the superspin formalism. These numbers are for infinitely short pulses on resonance and without relaxation or diffusion, but the extension to real systems is also discussed. In particular, it is shown that the attenuation down the echo train is due to a varying contribution from bothT1andT2processes, as well as diffusion. With longT1’s and slow diffusion, the decay of the echoes approximatesT2.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"123 1","pages":"Pages 49-55"},"PeriodicalIF":0.0,"publicationDate":"1996-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0212","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91775690","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: 30

Single-Point Ramped Imaging withT1Enhancement (SPRITE) t1增强单点斜坡成像(SPRITE)

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0225

B.J. Balcom , R.P. Macgregor , S.D. Beyea , D.P. Green , R.L. Armstrong , T.W. Bremner

引用次数: 305

Fractional-Frequency Peaks in Two-Pulse 2D Experiments under Strong Radiation Damping 强辐射阻尼下双脉冲二维实验中的分数频率峰

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0224

Jin-Hong Chen, Xi-An Mao , Chao-Hui Ye

引用次数: 11

New PFG NMR Spectrometer with a Rotatable Quadrupole Coil for the Measurement of an Anisotropic Self-Diffusion Coefficient Tensor 用于测量各向异性自扩散系数张量的新型可旋转四极线圈PFG核磁共振光谱仪

Journal of Magnetic Resonance, Series A Pub Date : 1996-11-01 DOI: 10.1006/jmra.1996.0214

Osamu Oishi, Seiichi Miyajima

引用次数: 11