Journal ArticleDOI
Double-quantum homonuclear correlation magic angle sample spinning nuclear magnetic resonance spectroscopy of dipolar-coupled quadrupolar nuclei.
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TLDR
A central-transition-selective pi pulse at the beginning of the t1 evolution period differentiates coherence transfer pathways of double-quantum coherences arising from coupled spins and from a single spin, so that the latter can be efficiently filtered out by phase cycling.Abstract:
A double-quantum homonuclear correlation nuclear magnetic resonance experiment for dipolar-coupled half-integer quadrupolar nuclei in solids is presented. The experiment is based on rotary resonance dipolar recoupling and uses bracketed spin-lock pulses to excite double-quantum coherence and later to convert it to the zero-quantum one. A central-transition-selective π pulse at the beginning of the t1 evolution period differentiates coherence transfer pathways of double-quantum coherences arising from coupled spins and from a single spin, so that the latter can be efficiently filtered out by phase cycling. The experiment was tested on an aluminophosphate molecular sieve AlPO4-14, a material with a variety of aluminum quadrupolar coupling constants, isotropic chemical shifts and homonuclear distances. In a two-dimensional spectrum aluminum dipolar couplings with internuclear distances between 2.9 and 5.5 A were resolved. Although the experiment requires an application of weak radio-frequency fields, frequency offsets did not affect its performance crucially.read more
Citations
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Journal ArticleDOI
Insights into the Dealumination of Zeolite HY Revealed by Sensitivity-Enhanced 27Al DQ-MAS NMR Spectroscopy at High Field
Journal ArticleDOI
Recent advances in application of 27Al NMR spectroscopy to materials science
TL;DR: An overview of results obtained by (27)Al NMR as well as the most relevant methodological developments over the last 25years are presented, concerning particularly on progress in the application of liquid- and solid-state NMR to the study of aluminum-based materials such as aluminum polyoxoanions, zeolites, aluminophosphates, and metal-organic-frameworks.
Journal ArticleDOI
NMR studies of oxide-based glasses
TL;DR: In this article, the authors present a review of the advances reported in the literature for characterizing the structures of oxide-based glasses over roughly the past 15 years, focusing on the progress made for revealing intermediate-range structural order, such as extracting information about connectivities among the basic building blocks in the glass networks and how more extended structural motifs may be identified.
Journal ArticleDOI
Structural information from quadrupolar nuclei in solid state NMR
TL;DR: A review of the state-of-the-art for quadrupolar NMR is given in this paper, where the advantages and disadvantages of various experiments for different possible applications are assessed.
Journal ArticleDOI
Bronsted/Lewis Acid Synergy in H-ZSM-5 and H-MOR Zeolites Studied by (1)H and (27)Al DQ-MAS Solid-State NMR Spectroscopy
TL;DR: In this paper, the spatial proximities of acid sites in dealuminated H-MOR and H-ZSM-5 zeolites have been comprehensively studied by two-dimensional H-1 and Al-27 double-quantum magic-angle spinning (DQ-MAS) spectroscopy.
References
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Journal ArticleDOI
Chemical shift correlation spectroscopy in rotating solids: Radio frequency‐driven dipolar recoupling and longitudinal exchange
TL;DR: In this paper, a new method of performing chemical shift correlation spectroscopy in solids with magic angle spinning (MAS) is presented. But the method is not suitable for the case of alanine.
Journal ArticleDOI
Broadband dipolar recoupling in the nuclear magnetic resonance of rotating solids: A compensated C7 pulse sequence
TL;DR: In this paper, an improved variant of the C7 pulse-sequence for efficient recoupling of spin-1/2 pair dipolar interactions in magic-angle spinning solid-state NMR spectroscopy is introduced.
Journal ArticleDOI
Double‐quantum homonuclear rotary resonance: Efficient dipolar recovery in magic‐angle spinning nuclear magnetic resonance
TL;DR: In this paper, a double-quantum homonuclear rotary resonance (2Q•HORROR) was established by fulfilling the condition ωr=2ω1, where ω r is the sample rotation frequency and ω 1 is the nutation frequency around an applied resonant radio frequency (RF) field.
Journal ArticleDOI
Efficient dipolar recoupling in the NMR of rotating solids. A sevenfold symmetric radiofrequency pulse sequence
TL;DR: In this paper, a new radiofrequency pulse sequence was introduced for the efficient reintroduction of magnetic dipolar couplings in the magic-angle-spinning NMR of solids.
Journal ArticleDOI
Fictitious spin 1/2 operator formalism for multiple quantum NMR
TL;DR: In this article, a formalism is presented that describes the time behavior of the spin density matrix of a nuclear spin system with arbitrary spin in terms of fictitious spin −(1/2) operators.
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