scholarly journals Origin of the Residual Linewidth Under FSLG-Based Homonuclear Decoupling in MAS Solid-State NMR

2019 ◽  
Author(s):  
Johannes Hellwagner ◽  
Liam Grunwald ◽  
Manuel Ochsner ◽  
Daniel Zindel ◽  
Beat H. Meier ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Floquet Theory ◽  
Pulse Sequence ◽  
Field Inhomogeneity ◽  
Line Broadening ◽  
Third Order ◽  
Order Error ◽  
Homonuclear Decoupling ◽  
Error Terms

Abstract. Homonuclear decoupling sequences in solid-state NMR under magic-angle spinning (MAS) show experimentally significantly larger residual linewidth than expected from Floquet theory to second order. We present an in-depth theoretical and experimental analysis of the origin of the residual linewidth in frequency-switched Lee-Goldburg (FSLG) based decoupling sequences. We analyze the effect of experimental pulse-shape errors (e.g. pulse transients and B1-field inhomogeneities) and use a Floquet-theory based description of higher-order error terms that arise from the interference between the MAS rotation and the pulse sequence. It is shown that the magnitude of the third-order auto term of a single homo- or heteronuclear coupled spin pair is important and leads to significant line broadening under FSLG decoupling. Furthermore, we show the dependence of these third-order error terms on the angle of the effective field with the B0 field. An analysis of second-order cross terms is presented that shows that the influence of three-spin terms is small since they are averaged by the pulse sequence. The importance of the static rf-field inhomogeneity is discussed and shown to be the main source of residual line broadening while pulse transients do not seem to play an important role. Experimentally, the influence of the combination of these error terms is shown by using restricted samples and pulse-transient compensation. The results show that all terms are additive but the major contribution to the residual linewidth comes from the rf-field inhomogeneity for the standard implementation of FSLG sequences, which is significant even for samples with a restricted volume.

scholarly journals Origin of the residual line width under frequency-switched Lee–Goldburg decoupling in MAS solid-state NMR

2020 ◽  
Vol 1 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Johannes Hellwagner ◽  
Liam Grunwald ◽  
Manuel Ochsner ◽  
Daniel Zindel ◽  
Beat H. Meier ◽  
...  
Keyword(s):  
Solid State ◽  
Line Width ◽  
Floquet Theory ◽  
Pulse Sequence ◽  
Second Order ◽  
Magic Angle ◽  
Line Broadening ◽  
Third Order ◽  
Order Error ◽  
Error Terms

Abstract. Homonuclear decoupling sequences in solid-state nuclear magnetic resonance (NMR) under magic-angle spinning (MAS) show experimentally significantly larger residual line width than expected from Floquet theory to second order. We present an in-depth theoretical and experimental analysis of the origin of the residual line width under decoupling based on frequency-switched Lee–Goldburg (FSLG) sequences. We analyze the effect of experimental pulse-shape errors (e.g., pulse transients and B1-field inhomogeneities) and use a Floquet-theory-based description of higher-order error terms that arise from the interference between the MAS rotation and the pulse sequence. It is shown that the magnitude of the third-order auto term of a single homo- or heteronuclear coupled spin pair is important and leads to significant line broadening under FSLG decoupling. Furthermore, we show the dependence of these third-order error terms on the angle of the effective field with the B0 field. An analysis of second-order cross terms is presented that shows that the influence of three-spin terms is small since they are averaged by the pulse sequence. The importance of the inhomogeneity of the radio-frequency (rf) field is discussed and shown to be the main source of residual line broadening while pulse transients do not seem to play an important role. Experimentally, the influence of the combination of these error terms is shown by using restricted samples and pulse-transient compensation. The results show that all terms are additive but the major contribution to the residual line width comes from the rf-field inhomogeneity for the standard implementation of FSLG sequences, which is significant even for samples with a restricted volume.

scholarly journals Use of Solid-State NMR Spectroscopy for the Characterization of Molecular Structure and Dynamics in Solid Polymer and Hybrid Electrolytes

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1207
Author(s):  
Gabrielle Foran ◽  
Nina Verdier ◽  
David Lepage ◽  
Cédric Malveau ◽  
Nicolas Dupré ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Pulse Sequence ◽  
Dynamic Properties ◽  
Double Resonance ◽  
Solid Polymer ◽  
Pulse Field ◽  
Solid State Nmr Spectroscopy

Solid-state NMR spectroscopy is an established experimental technique which is used for the characterization of structural and dynamic properties of materials in their native state. Many types of solid-state NMR experiments have been used to characterize both lithium-based and sodium-based solid polymer and polymer–ceramic hybrid electrolyte materials. This review describes several solid-state NMR experiments that are commonly employed in the analysis of these systems: pulse field gradient NMR, electrophoretic NMR, variable temperature T1 relaxation, T2 relaxation and linewidth analysis, exchange spectroscopy, cross polarization, Rotational Echo Double Resonance, and isotope enrichment. In this review, each technique is introduced with a short description of the pulse sequence, and examples of experiments that have been performed in real solid-state polymer and/or hybrid electrolyte systems are provided. The results and conclusions of these experiments are discussed to inform readers of the strengths and weaknesses of each technique when applied to polymer and hybrid electrolyte systems. It is anticipated that this review may be used to aid in the selection of solid-state NMR experiments for the analysis of these systems.

31P and 195Pt solid-state NMR and DFT studies on platinum(i) and platinum(ii) complexes

2018 ◽  
Vol 47 (27) ◽  
pp. 8884-8891 ◽  
Author(s):  
Stefano Todisco ◽  
Giacomo Saielli ◽  
Vito Gallo ◽  
Mario Latronico ◽  
Antonino Rizzuti ◽  
...  
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
Pulse Sequence ◽  
Spin Orbit ◽  
Dft Studies ◽  
Relativistic Dft

31P and 195Pt solid state NMR spectra on anti-[(PHCy)ClPt(μ-PCy2)2Pt(PHCy)Cl] (3) and [(PHCy2)Pt(μ-PCy2)(κ2P,O-μ-POCy2)Pt(PHCy2)] (Pt–Pt) (4) were recorded under CP/MAS conditions (31P) or with the CP/CPMG pulse sequence (195Pt) and compared to data obtained by relativistic DFT calculations of 31P and 195Pt CS tensors and isotropic shielding at the ZORA Spin Orbit level.

Interference of homonuclear decoupling and exchange in the solid-state NMR of perfluorocyclohexane

2003 ◽  
Vol 161 (2) ◽  
pp. 234-241 ◽  
Author(s):  
Deborah E. McMillan ◽  
Paul Hazendonk ◽  
Paul Hodgkinson
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Homonuclear Decoupling

ChemInform Abstract: Operator-Based Floquet Theory in Solid-State NMR

ChemInform ◽  
2010 ◽  
Vol 41 (48) ◽  
pp. no-no
Author(s):  
Ingo Scholz ◽  
Jacco D. van Beek ◽  
Matthias Ernst
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Floquet Theory ◽  
Abstract Operator

scholarly journals Residual Linewidth in Magic-Angle Spinning Solid-State NMR

2021 ◽  
Author(s):  
Matías Chávez ◽  
Thomas Wiegand ◽  
Alexander A. Malär ◽  
Beat H. Meier ◽  
Matthias Ernst
Keyword(s):  
Line Width ◽  
Solid State Nmr ◽  
Magic Angle Spinning ◽  
Spin Systems ◽  
Second Order ◽  
Magic Angle ◽  
Line Broadening ◽  
Third Order ◽  
Angle Spinning ◽  
Effective Hamiltonians

Abstract. Magic-angle spinning is routinely used to average anisotropic interactions in solid-state NMR. Due to the fact, that the Hamiltonian of a strongly-coupled spin system does not commute with itself at different time points during the rotation, second-order and higher-order terms lead to a residual line broadening in the observed resonances. Additional truncation of the residual broadening due to isotropic chemical-shift differences can be observed. We analyze the residual line broadening in coupled proton spin systems based on theoretical calculations of effective Hamiltonians up to third order using Floquet theory and compare these results to numerically obtained effective Hamiltonians in small spin systems. We show that at spinning frequencies beyond 50 kHz, second-order terms dominate the residual line width leading to a 1/ωr dependence of the second moment which we use to characterize the line width. However, chemical-shift truncation leads to a partial ωr-2 dependence of the line width which looks as if third-order effective Hamiltonian terms are contributing significantly. We show that second-order contributions not only broaden the line but also lead to a shift of the center of gravity of the line. Experimental data reveals such spinning-frequency dependent line shifts in proton spectra in model substances that can be explained by line shifts induced by the second-order dipolar Hamiltonian.

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