Journal of Magnetic Resonance (1969)最新文献_第7页

The pseudo-wigner distribution of double and triple resonances 双共振和三重共振的伪维格纳分布

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90375-H

J.H.J Leclerc

引用次数: 3

Theoretical treatment of relaxation in the presence of an RF field 射频场存在下弛豫的理论处理

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90362-B

Scott A Smith, William E Palke, J.T Gerig

引用次数: 6

A deuteron NMR study of neopentane adsorbed on graphite. An example for the dominance of the magnetic shielding over the electric quadrupole coupling 石墨吸附新戊烷的氘核磁共振研究。磁屏蔽优于电四极耦合的一个例子

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90368-H

G Auer, B Boddenberg

{"title":"A deuteron NMR study of neopentane adsorbed on graphite. An example for the dominance of the magnetic shielding over the electric quadrupole coupling","authors":"G Auer, B Boddenberg","doi":"10.1016/0022-2364(92)90368-H","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90368-H","url":null,"abstract":"<div>The deuteron NMR spectra and spin-lattice relaxation times of neopentane adsorbed on the graphitized carbon black Graphon at surface coverages between 0.1 and 1.2 were measured at two different Zeeman fields (2.1 and 8.1 T) in the temperature range 80–290 K. For comparison purposes the 2H NMR spectra were measured for neopentane on boron nitride, on the nongraphitized carbon black Spheron, and on the graphitized carbon black Sterling MT. The spectra of neopentane on the graphitized carbon blacks in the Zeeman field B0 = 8.1 T are practically completely determined by an extramolecular magnetic shielding-type coupling arising from the anisotropic polarization of the graphite support. The spin-lattice relaxation times are dominated at temperatures of 80 to 150 K by the quadrupole coupling, whereas above 150 K the anisotropic shielding coupling dominates at high Zeeman field. The analysis of the spin-lattice relaxation times allows one to evaluate the reorientation times of the molecules about their center of gravity as well as the translational surface diffusion coefficients. The isotropic molecular reorientation rates were found to be of the same order of magnitude as those in the bulk liquid and plastic phases. The surface diffusion coefficients (about 5 × 10−8 m2 s−1 at the bulk melting temperature 256.6 K) are about one order of magnitude larger than those in the bulk liquid.</div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 88-100"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90368-H","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90014908","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

Gradient-enhanced multiple-quantum filter (ge-MQF). A simple way to obtain single-scan phase-sensitive HMQC spectra 梯度增强多量子滤波器(ge-MQF)。一种获得单扫描相敏HMQC光谱的简单方法

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90381-G

Geerten W Vuister , Jesús Ruff-Cabello , Peter C.M van Zijl

引用次数: 22

Ultra-high-resolution multiple-pulse 1H NMR of organic conductors 有机导体的超高分辨率多脉冲1H NMR

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90367-G

A.C Kolbert, M Mehring

引用次数: 0

Comparison of the coherence-transfer efficiencies of laboratory- and rotating-frame experiments 实验室与旋转框架实验的相干传递效率比较

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90365-E

A Ramamoorthy, N Chandrakumar

{"title":"Comparison of the coherence-transfer efficiencies of laboratory- and rotating-frame experiments","authors":"A Ramamoorthy, N Chandrakumar","doi":"10.1016/0022-2364(92)90365-E","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90365-E","url":null,"abstract":"<div>Coherence transfer under INEPT and isotropic mixing is quantified theoretically and the predictions are verified by experiments on various homonuclear spin systems. A general expression for magnetization transfer is derived for INEPT in AMXN systems, in terms of the “leaving fraction,” trigonometric function, “spin multiplier,” and “attenuation factor.” In general, coherence transfer under INEPT is not identical from AM to XN and XN to AM when M ≠ N. Unlike INEPT, in the case of isotropic mixing all magnetization components are conserved for the spin system as a whole, transfer is in-phase, and the m = 0 component of spin multiplets also plays a role in coherence transfer, leading to advantages over INEPT under conditions of unresolved couplings and integer composite angular momenta. Coherence-transfer efficiencies of these experiments are compared with the predicted universal bound on spin dynamics.</div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 60-68"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90365-E","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91632260","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: 11

Kinetics of the in vivo31P1H nuclear overhauser effect of the human-calf-muscle phosphocreatine resonance 人-小腿肌磷酸肌酸共振的体内31p1H核大修效应动力学

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90372-E

Peter Bachert, Matthias E Bellemann

引用次数: 21

Hyperfine-axis orientation in rhombic metal complexes from ENDOR-induced EPR and quadrupolar coupling determination 从内啡肽诱导的EPR和四极偶联测定中，超细轴取向的菱形金属配合物

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90364-D

S.P Greiner , R.W Kreilick

{"title":"Hyperfine-axis orientation in rhombic metal complexes from ENDOR-induced EPR and quadrupolar coupling determination","authors":"S.P Greiner , R.W Kreilick","doi":"10.1016/0022-2364(92)90364-D","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90364-D","url":null,"abstract":"<div>The ENDOR resonances from ligand nuclei in paramagnetic transition-metal complexes exhibit a shift from the nuclear Larmor frequency because of the dipolar and Fermi contact interactions with the unpaired electron. The dipolar interaction has orientation dependence associated with its magnitude, where the position of the nuclei with respect to the metal atom determines the resonant frequencies and spectral lineshape. In this paper effects of rhombic g and metal hyperfine tensors on the EPR powder pattern and ENDOR spectra are illustrated. The EPR angular selection is modified from that encountered in axial systems and the technique of ENDOR-induced EPR is utilized to elucidate the orientation of magnetic axes with respect to one another. Quadrupole couplings in ENDOR spectra have often been analyzed using an equation from which cross terms have been omitted. The cross terms make important contributions to the spectra in some cases and the effect of these terms has been examined in order to determine when the complete equation for the quadrupole interaction must be utilized to analyze correctly ENDOR spectra.</div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 43-59"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90364-D","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91678224","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}

引用次数: 4

Indirect detection via the dipolar demagnetizing field 通过偶极退磁场间接检测

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90361-A

R Bowtell

{"title":"Indirect detection via the dipolar demagnetizing field","authors":"R Bowtell","doi":"10.1016/0022-2364(92)90361-A","DOIUrl":"https://doi.org/10.1016/0022-2364(92)90361-A","url":null,"abstract":"<div>A new method for indirectly detecting the magnetization of one spin species via the NMR signal of a second species is described. This method, which does not require that the spins of the two species be chemically coupled or even on the same molecule, relies on the nonlinear effect of the demagnetizing field produced by the nuclei themselves. It involves allowing I spins belonging to one spin species to precess under the influence of the demagnetizing field produced by S spins of a different species. The demagnetizing field generates an echo of the I magnetization. This echo carries information about the state of S magnetization and so offers a method of indirect detection. In certain circumstances this method can yield a signal-to-noise ratio higher than that given by direct detection. To demonstrate the process of echo formation, experiments have been carried out at 11.7 T on an aqueous solution of 13C-enriched potassium cyanide. Here the water protons form the I spins, while the 13C nuclei in the cyanide group form the S spins. The experimental results are in agreement with the theory outlined in this paper. Experimental methods which allow the application of this form of indirect detection to spectroscopy and imaging are also described.</div>","PeriodicalId":100800,"journal":{"name":"Journal of Magnetic Resonance (1969)","volume":"100 1","pages":"Pages 1-17"},"PeriodicalIF":0.0,"publicationDate":"1992-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0022-2364(92)90361-A","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91678251","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: 75

Analysis of inversion-magnetization-transfer experiments 反磁化转移实验分析

Journal of Magnetic Resonance (1969) Pub Date : 1992-10-15 DOI: 10.1016/0022-2364(92)90376-I

S.V Santhana Mariappan, Dallas L Rabenstein

引用次数: 10