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13C Nuclear Spin Relaxation Study of 1-Bromo-2-phenylacetylene. Determination of Carbon–Bromine Scalar Coupling Constant Including Its Sign 1-溴-2-苯乙炔13C核自旋弛豫研究。含符号的碳溴标量耦合常数的测定
Journal of Magnetic Resonance, Series A Pub Date : 1996-10-01 DOI: 10.1006/jmra.1996.0200
Andrzej Ejchart , Adam Gryff-Keller
{"title":"13C Nuclear Spin Relaxation Study of 1-Bromo-2-phenylacetylene. Determination of Carbon–Bromine Scalar Coupling Constant Including Its Sign","authors":"Andrzej Ejchart , Adam Gryff-Keller","doi":"10.1006/jmra.1996.0200","DOIUrl":"10.1006/jmra.1996.0200","url":null,"abstract":"","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 2","pages":"Pages 233-236"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85837617","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
Quadrupole Coupling and Anisotropic Shielding from Single-Crystal NMR of the Central Transition for Quadrupolar Nuclei.87Rb NMR of RbClO4and Rb2SO4 四极耦合及四极核中心跃迁单晶核磁共振各向异性屏蔽。rbclo4和Rb2SO4的87rb核磁共振
Journal of Magnetic Resonance, Series A Pub Date : 1996-10-01 DOI: 10.1006/jmra.1996.0186
Thomas Vosegaard, Jørgen Skibsted, Henrik Bildsøe, Hans J. Jakobsen
{"title":"Quadrupole Coupling and Anisotropic Shielding from Single-Crystal NMR of the Central Transition for Quadrupolar Nuclei.87Rb NMR of RbClO4and Rb2SO4","authors":"Thomas Vosegaard,&nbsp;Jørgen Skibsted,&nbsp;Henrik Bildsøe,&nbsp;Hans J. Jakobsen","doi":"10.1006/jmra.1996.0186","DOIUrl":"10.1006/jmra.1996.0186","url":null,"abstract":"<div><p>The possibility of retrieving parameters for the combined effect of quadrupole coupling and small chemical-shielding anisotropies from single-crystal NMR of the central transition for half-integer quadrupolar nuclei has been successfully investigated.<sup>87</sup>Rb single-crystal NMR of RbClO<sub>4</sub>and Rb<sub>2</sub>SO<sub>4</sub>serve as two properly chosen and illustrative examples. Thereby, discrepancies between some of the<sup>87</sup>Rb parameters recently reported for these two interactions in powders of RbClO<sub>4</sub>and Rb<sub>2</sub>SO<sub>4</sub>, and determined from MAS and static powder NMR, have been clarified. The orientations of the crystallographic axes for the two rubidium crystals have been predicted by the NMR results and verified independently by XRD analysis.</p></div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 2","pages":"Pages 111-119"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0186","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86399170","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: 41
Estimation of the Characteristic Length Scales forB0Variation Using the OE-CTPG Pulse Sequence 利用OE-CTPG脉冲序列估计b0变化的特征长度尺度
Journal of Magnetic Resonance, Series A Pub Date : 1996-10-01 DOI: 10.1006/jmra.1996.0198
Mark A. Horsfield , Simon A. Clark , Timothy J. Norwood
{"title":"Estimation of the Characteristic Length Scales forB0Variation Using the OE-CTPG Pulse Sequence","authors":"Mark A. Horsfield ,&nbsp;Simon A. Clark ,&nbsp;Timothy J. Norwood","doi":"10.1006/jmra.1996.0198","DOIUrl":"10.1006/jmra.1996.0198","url":null,"abstract":"<div><p>NMR measurement of diffusion is a well-established tool for investigating the microstructure of heterogeneous materials. Since an applied magnetic-field gradient is an essential element of the pulse sequences usually used, any magnetic-field gradients present within the sample may interfere with the NMR measurement, in some cases making it impracticable. Here, a method that uses the internal gradients themselves to provide information about the heterogeneous structure, in materials where these gradients are strong, is described. The technique is demonstrated using a range of solvents in packs of different sizes of glass beads.</p></div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 2","pages":"Pages 222-229"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0198","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76407579","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: 0
Fluid Transport in Porous Rocks. I. EPI Studies and a Stochastic Model of Flow 多孔岩石中的流体输运。1 . EPI研究与流动的随机模型
Journal of Magnetic Resonance, Series A Pub Date : 1996-10-01 DOI: 10.1006/jmra.1996.0189
P. Mansfield , B. Issa
{"title":"Fluid Transport in Porous Rocks. I. EPI Studies and a Stochastic Model of Flow","authors":"P. Mansfield ,&nbsp;B. Issa","doi":"10.1006/jmra.1996.0189","DOIUrl":"10.1006/jmra.1996.0189","url":null,"abstract":"<div><p>The velocity of water flowing through a Bentheimer sandstone core has been measured by NMR-imaging techniques. The localized pixel values of velocity indicate a random distribution centered around the mean value corresponding to Darcy's law. When the same flow state is repeated, the velocity map changes but the general characteristics of the velocity distribution remain unchanged. The random nature of the irreproducibility of the flow maps has led us to propose a stochastic theory of flow in porous rocks. The theory leads to a Gaussian velocity distribution which approximates well to the data. Also predicted is a linear relationship between flow variance and mean fluid flow through the rock, the Mansfield–Issa equation, originally proposed as an empirical relationship.</p></div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 2","pages":"Pages 137-148"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0189","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85211341","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: 42
Fluid Transport in Porous Rocks. II. Hydrodynamic Model of Flow and Intervoxel Coupling 多孔岩石中的流体输运。2流体力学模型与体素间耦合
Journal of Magnetic Resonance, Series A Pub Date : 1996-10-01 DOI: 10.1006/jmra.1996.0190
P. Mansfield , B. Issa
{"title":"Fluid Transport in Porous Rocks. II. Hydrodynamic Model of Flow and Intervoxel Coupling","authors":"P. Mansfield ,&nbsp;B. Issa","doi":"10.1006/jmra.1996.0190","DOIUrl":"10.1006/jmra.1996.0190","url":null,"abstract":"<div><p>In a preceding paper [P. Mansfield and B. Issa,<em>J. Magn. Reson. A</em>122, 137–148 (1996)], a stochastic model of fluid flow in porous rocks based upon the experimental observation of water flow through a Bentheimer sandstone core was proposed. The flow maps were measured by NMR-imaging techniques. The stochastic theory led to a Gaussian velocity distribution with a mean value in accord with Darcy's law. Also predicted was a linear relationship between flow variance and mean fluid flow through rock, the Mansfield–Issa equation, originally proposed as an empirical relationship. In the present work a flow coupling mechanism between voxels is proposed. Examination of the flow coupling between isolated voxel pairs leads to a complementary explanation of the Gaussian velocity distribution, and also gives further details of the Mansfield–Issa equation. These details lead to a new expression for the connectivity, 〈<em>C</em>〉, between voxels with an experimental value of 〈<em>C</em>〉 = 5.64 × 10<sup>−9</sup>for Bentheimer sandstone.</p></div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 2","pages":"Pages 149-156"},"PeriodicalIF":0.0,"publicationDate":"1996-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0190","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83562610","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: 10
Proton Spin–Lattice Relaxation in Monocrystalline Ammonium Chloride 单晶氯化铵中质子自旋-晶格弛豫
Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0168
F.I. Bashirov
{"title":"Proton Spin–Lattice Relaxation in Monocrystalline Ammonium Chloride","authors":"F.I. Bashirov","doi":"10.1006/jmra.1996.0168","DOIUrl":"10.1006/jmra.1996.0168","url":null,"abstract":"New symmetry-adapted autocorrelation functions are used in the theoretical description of the nuclear magnetic dipole–dipole relaxation in molecular crystals. They are obtained in the model frame that a molecule rotates by means of the finite angular jumps between the hindered states of the same symmetry in different potential wells. The experimental data of the temperature dependence of the proton relaxation timesT1andT1ρin the mono- and polycrystalline NH4Cl are revised. As a result, it is proposed to classify the NH+4ion motion by two kinds of the hindered states corresponding to the two-dimensional (E) and three-dimensional (F) irreducible representations of a point group of the cubic system. The dynamical weight of the stateFis defined to be equal to 0.25 and that of the stateEto be equal to 0.73 from the experiments in the ordered phase of NH4Cl. Based on abstract geometric groups, the respective weights are 0.4 and 0.6. This discrepancy in the weights of the states is explained by the effect of the tetragonal distortion of the tetrahedral site symmetry of the NH+4ion. The result of the prevalence of aC3reorientation in comparison to aC2reorientation of the ion is also justified. Because of the absence of the experimental temperature minima ofT1orT1ρ, assumptions are only made about the dynamical parameters of the NH+4ion motion in the disordered phase of NH4Cl.","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 1-8"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0168","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87772721","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
Improving the Field-Variable External Lock for an Electromagnet 电磁体场变外锁的改进
Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0178
R. Sitnikov, I. Furó, U. Henriksson
{"title":"Improving the Field-Variable External Lock for an Electromagnet","authors":"R. Sitnikov,&nbsp;I. Furó,&nbsp;U. Henriksson","doi":"10.1006/jmra.1996.0178","DOIUrl":"10.1006/jmra.1996.0178","url":null,"abstract":"","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 76-77"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0178","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88484506","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: 3
Detection of Intermolecular Heteronuclear Multiple-Quantum Coherences in Solution NMR 溶液核磁共振中分子间异核多量子相干的检测
Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0183
Patricia R. Bachiller, Sangdoo Ahn, Warren S. Warren
{"title":"Detection of Intermolecular Heteronuclear Multiple-Quantum Coherences in Solution NMR","authors":"Patricia R. Bachiller,&nbsp;Sangdoo Ahn,&nbsp;Warren S. Warren","doi":"10.1006/jmra.1996.0183","DOIUrl":"10.1006/jmra.1996.0183","url":null,"abstract":"","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 94-99"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0183","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75910778","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: 28
EPR, Electron Spin–Lattice Relaxation, and Debye Temperature of Cu(II)-Doped Triglycine Selenate Crystal 铜(II)掺杂硒酸三甘氨酸晶体的电子自旋-晶格弛豫和德拜温度
Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0171
StanisŁaw K. Hoffmann, Wojciech Hilczer, Janina Goslar
{"title":"EPR, Electron Spin–Lattice Relaxation, and Debye Temperature of Cu(II)-Doped Triglycine Selenate Crystal","authors":"StanisŁaw K. Hoffmann,&nbsp;Wojciech Hilczer,&nbsp;Janina Goslar","doi":"10.1006/jmra.1996.0171","DOIUrl":"10.1006/jmra.1996.0171","url":null,"abstract":"<div><p>Single-crystal rotational data of CW-EPR and two-pulse field-swept ESE collected at room and low temperatures lead to the spin-Hamiltonian parameters<em>g</em><sub><em>z</em></sub>= 2.2596,<em>g</em><sub><em>y</em></sub>= 2.0647,<em>g</em><sub><em>x</em></sub>= 2.0529,<em>A</em><sub><em>z</em></sub>= 151.2 × 10<sup>−4</sup>cm<sup>−1</sup>,<em>A</em><sub><em>y</em></sub>= 2.5 × 10<sup>−4</sup>cm<sup>−1</sup>, and<em>A</em><sub><em>x</em></sub>= 42.2 × 10<sup>−4</sup>cm<sup>−1</sup>which are temperature independent. The parameters and Cu<sup>2+</sup>ion site in the crystal unit cell are very similar to those in the triglycine sulfate crystal. Electron-spin-echo measurements of the spin–lattice relaxation time<em>T</em><sub>1</sub>in the temperature range 4.2–90 K gave identical results for inversion- and saturation-recovery methods, indicating a negligible spectral-diffusion contribution. The<em>T</em><sub>1</sub>decreases from 275 μs at 15 K to 1.7 μs at 83 K and the temperature dependence is governed by the direct (one-phonon) process at low temperatures and two-phonon Raman process at higher temperatures. A new analytical form of the<em>I</em><sub>8</sub>transport integral of the Raman term is proposed. The best fit to the theoretical expression was found for the Debye temperature ϑ<sub>D</sub>= 168 ± 3 K which is comparable to ϑ<sub>D</sub>= 171 K calculated from the elastic constants of the crystal.</p></div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 37-41"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0171","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89581597","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: 16
Suppression of Cycling Sidebands Using Bi-level Adiabatic Decoupling 利用双能级绝热解耦抑制循环边带
Journal of Magnetic Resonance, Series A Pub Date : 1996-09-01 DOI: 10.1006/jmra.1996.0180
Ēriks Kupce , Ray Freeman , Gerhard Wider , Kurt Wüthrich
{"title":"Suppression of Cycling Sidebands Using Bi-level Adiabatic Decoupling","authors":"Ēriks Kupce ,&nbsp;Ray Freeman ,&nbsp;Gerhard Wider ,&nbsp;Kurt Wüthrich","doi":"10.1006/jmra.1996.0180","DOIUrl":"10.1006/jmra.1996.0180","url":null,"abstract":"","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"122 1","pages":"Pages 81-84"},"PeriodicalIF":0.0,"publicationDate":"1996-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0180","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90592676","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: 43
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