Principles of High Resolution NMR in Solids - M Mehring
Improved Peptide and Protein Torsional - CiteSeerX
long nuclear spin–lattice relaxation times T1 in the liquid state. Although conventional NMR spectra of amorphous solids reveal no structural information due to large dipolar interactions, the use of high power cross-polarization (CP) techniques 1 has overcome However, the problems with weak signals can be largely overcome by using cross polarization pulse sequences (Pines et al. 1973), and the broad linewidths can be sharpened by spinning samples at the “magic angle” of 54.7° relative to the applied magnetic field (Schaefer and Stejskal 1976). 2020-11-12 Cross-Polarization 622 4. Practical Considerations 626 5. Conclusions 627 6. Acknowledgments 627 7.
Cross polarization enhances signal from dilute spins Optimization of cross-polarization at low radiofrequency fields for sensitivity enhancement in solid-state NMR of membrane proteins reconstituted in magnetically aligned bicelles. Koroloff SN(1), Nevzorov AA(2). Author information: (1)Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, USA. 2020-09-14 Cross Polarization Cross polarization is one of the most important techniques in solid state NMR. In this technique, polarization from abundant spins such as 1H or 19F is transferred to dilute spins such as 13C or 15N. The overall effect is to enhance S/N: 1. Cross polarization enhances signal from dilute spins The spin-bearing particles can be homo- or hetero-nuclei or, in principle, even unpaired electrons.
In Sec. II we review briefly the spin thermody-namics of cross-polarization experiments So far, most NMR or MRI studies based on dissolution DNP [1] free radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) is fast, have focused on nuclear spins such as 13C, 15N, 89Y, etc., that have one can quickly obtain intense 13C signals after cross-polarization. long nuclear spin–lattice relaxation times T1 in the liquid state.
The Multinuclear Approach to NMR Spectroscopy – J B
To make the problem more concrete, Fig. 1 shows a schematic of the general approach. Two extreme cases may be considered: "multiple cross-polarization" and "total cross-polarization". In the first, a small amount of I polarization is transferred to the 8 spins and the cycle is repeated many times as indicated, with the 8 such NMR cross-polarization experiments between abundant nuclei with spin I=—,' and rare nuclei with S= 1. %'e show experimentally and theoretically that it is indeed possible to polarize the double-quantum transition of deuterium from protons in a solid.
A revised solid-state NMR met... - LIBRIS
The first stems from the fact that solid-state Overall, the cross- polarization approach appears to have considerable utility for aiding in the interpretation of “0 NMR spectra of complex inorganic solids. 0 1988 Academic PBS, Inc. No new theory is presented; rather several common analytical methods in SSNMR are demonstrated in the context of cross‐polarization under static and magic‐angle spinning (MAS) conditions. A background in NMR and quantum mechanics is assumed, however this work attempts to minimize the need for excursions into the literature. The Hartmann-Hahn matching profile in CP-MAS NMR shows a strong mismatch dependence if the MAS frequency is on the order of the dipolar couplings in the sample.
We find this methodology results in enhancement faetors of approximately 103 upon application to surface protons. The dynamics of 129Xe transfer to protons
double-cross-polarization-magic angle-spinning (2-D DCP MAS) NMR. During this experiment, magnetiza-tion is transferred first from 1Hto15N and then to 13C. The resulting spectrum shows cross peaks correlating 15N signal intensity to 13C chemical shifts of carbons that have strong dipolar interactions with neighboring 15N. Although CP has long been in common use for MAS NMR,the more recent pushes to very high rotation rates (above 40 kHz), or for cross polarization between rare spin-½ nuclei at lower rotation rates, requires more attention to experimental details like amplitude modulation, spin nutation frequencies on the nuclei pools and their relation to the mechanical sample rotation. Solid-state nuclear magnetic resonance (NMR) is used to analyze the structure and dynamics of polymers. In solid-state NMR, cross polarization (CP)/magic angle spinning (MAS) 1 is the most
Barth-Jan van Rossum: Solid-State NMR Cross polarization (CP) this approach is valid as long: 1. system contains a large number of spins 2.
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The overall effect is to enhance S/N: 1.
The use of cross‐polarization (CP) NMR in conjunction with magic angle sample spinning (MASS) to examine the hydration reaction of tricalcium silicate (C 3 S) is described.
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A revised solid-state NMR method to assess the crystallinity of
Cross polarization is a technique where magnetization is transferred from an abundant proton source to a dilute (isotopically of chemically) nucleus, X, during a "contact" period. The technique of cross polarization (CP) has since become immensely important in the practice of solid state NMR. Perhaps the greatest value of CP is in enhancing the signals of low gamma nuclei (13Cor 15N) that are dipolar coupled to proton spin baths. In addition, the modern development of CP has led to Solid-state 13C cross-polarization/magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy is a strong tool to investigate the structural features and dynamics of solid Measurement of NMR Cross-Polarization (CP) Rate Constants in the Slow CP Regime: Relevance to Structure Determinations of Zeolite−Sorbate and Other Complexes by CP Magic-Angle Spinning NMR. The Journal of Physical Chemistry A 2005, 109 (28) , 6187-6192. https://doi.org/10.1021/jp051923p This permits the kind of quantitative analysis of components practiced in solution NMR, e.g. Cross Polarization Magic-Angle Spinning (CP-MAS) By combining cross polarization with MAS, high resolution spectra can be obtained for rigid solids.