29Si and 17O (Q)CPMG-MAS solid-state NMR experiments as an optimum approach for half-integer nuclei having long T1 relaxation times

Larsen, Flemming H.; Farnan, Ian

doi:10.1016/s0009-2614(02)00520-1

Cited by 85 publications

(55 citation statements)

References 14 publications

(21 reference statements)

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“…Because glasses display inhomogeneously broadened lines, the free induction decay (FID) dies out quickly, but the signal can be refocused by a train of refocusing pulses, allowing for the collection of the signal over a much longer time, which results, in turn, in an increased sensitivity. In the case of inhomogeneous line broadening due to quadrupolar interactions in crystals, it has been shown that the collection of such an echotrain can increase sensitivity by an order of magnitude [11][12][13]. Also, an increase in sensitivity by a factor of 3 in the 29 Si NMR spectra of zeolites [14] has been observed.…”

Section: Introductionmentioning

confidence: 99%

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Increased 29Si NMR sensitivity in glasses with a Carr–Purcell–Meiboom–Gill echotrain

Malfait

Halter

2008

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 99%

“…The obtained spectra in the latter study however were distorted due to different T2 relaxation times for different sites. In addition, CPMG echotrains have been applied to collect the 29 Si NMR spectra of radiation-damaged zircons [11,15].…”

Section: Introductionmentioning

confidence: 99%

Increased 29Si NMR sensitivity in glasses with a Carr–Purcell–Meiboom–Gill echotrain

Malfait

Halter

2008

Journal of Non-Crystalline Solids

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“…The sample mass was 90 mg in average. 29 Si/ 1 H CP-MAS NMR spectra were collected using contact times ranging from 2-8 ms. 29 Si MAS NMR spectra were acquired, using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence 40 with a recycle delay ranging from 2 s for altered samples, which were found to relax faster owing to protons, and 20 s for pristine glasses.…”

mentioning

confidence: 99%

Impact of alkali on the passivation of silicate glass

et al. 2018

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Amorphous silica-rich surface layers, also called gels, can passivate silicate glass and minerals depending on environmental conditions. However, several uncertainties remain on the mechanisms controlling the formation of these layers. In this paper, the influence of exogenous ions supplied by solutions is studied, both on the formation and on the properties of the gel formed on international simple glass (ISG). ISG was altered at 90°C, pH 90°C 7, in silica-saturated solutions containing various alkaline cations separately (Li + , Na + , K + , and Cs + ). The alteration kinetics observed with Li and Na in the solution is similar to that observed with no ions, while K and Cs in the solution tend to decrease glass alteration. Furthermore, for K or Cs ions, the kinetics decreases as the ionic strength of the solution increases. The passivation layer formed in these solutions shows a selectivity toward cations following the series K > Cs > Na >> Li. These alkalis replace Ca from pristine glass in the altered structures, leading to differences in [AlO 4 ] − units charge compensation. Importantly, exchange between Ca and alkali also affects the total quantity of water inside each gel and this effect is well correlated with the observed drop in glass alteration.

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“…Larsen and Farnan (46) were the first to use the CPMG pulse sequence as a method of increasing the receptivity of the NMR experiment for spin-1/2 nuclei. More recently, we and others have shown that the CPMG technique can give significant S/N enhancements for spin-1/2 nuclei having broad powder patterns, such as 109 Ag,113 Cd, 195 Pt, 199 Hg, and 207 Pb, while retaining anisotropic magnetic shielding information (47,48).…”

Section: Application Of Multiple-pulse Spin-echo Experiments: Spin-1/mentioning

confidence: 99%

Signal-to-noise enhancement of NMR spectra of solids using multiple-pulse spin-echo experiments

Siegel

Nakashima

Wasylishen

2005

Concepts Magn. Reson.

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Three multiple-pulse spin-echo experiments that have been used to enhance the sensitivity of broad powder patterns obtained from NMR spectra of spin-1/2 and half-integer quadrupolar nuclei in polycrystalline solids are examined. Specifically, the Carr-Purcell Meiboom-Gill (CPMG), the Mansfield-Waugh (MW-4), and a modified version of the CPMG experiment (modified-CPMG) are described and compared. Use of these pulse sequences results in transforming the broad powder lineshapes into a series of narrow spikelets whose overall envelope mimics that obtained from the normal Hahn-echo experiment. The CPMG and modified-CPMG methods can result in a considerable saving in experiment time and are particularly powerful in studying the central transition of halfinteger spin quadrupolar nuclei. Artifacts generated by the MW-4 sequence or caused by imperfections in the pulses in the CPMG sequences are explained using a product operator analysis.

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29Si and 17O (Q)CPMG-MAS solid-state NMR experiments as an optimum approach for half-integer nuclei having long T1 relaxation times

Cited by 85 publications

References 14 publications

Increased 29Si NMR sensitivity in glasses with a Carr–Purcell–Meiboom–Gill echotrain

Increased 29Si NMR sensitivity in glasses with a Carr–Purcell–Meiboom–Gill echotrain

Impact of alkali on the passivation of silicate glass

Signal-to-noise enhancement of NMR spectra of solids using multiple-pulse spin-echo experiments

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