Double-quantum homonuclear correlations of spin I=5/2 nuclei

Mapping the oxygen structure of γ-Al2O3 by high-field solid-state NMR spectroscopy

“…4a ) shows that 73% of Al 3+ cations is in octahedral coordination, confirming that the vacancies are mainly at tetrahedral positions. This is also in agreement with previous 27 Al DQ-SQ experimental result on γ-Al 2 O 3 54 , where there is no correlation from two coupled tetrahedral 27 Al observed in the 2D 27 Al homonuclear correlation spectrum. It should be noted that the thermal treatment impacts to some extent the coordination of Al atom in γ-Al 2 O 3 .…”

Physical methods and techniques NMR spectroscopy

“…The optimized rotary resonance recoupling sequence, which allows for larger RF amplitude without exciting undesired DQ coherences, is used to measure the DQ-SQ homonuclear correlation spectra of YAG (yttrium aluminium garnet Y 3 Al 5 O 12 ) and gAl 2 O 3 . 108 Variable temperature and high-pressure 129 Xe NMR has been used to investigate the flexible and paramagnetic metal-organic framework Ni 2 (2,6-ndc) 2 (dabco) (DUT-8(Ni)1); DUT = Dresden University of Technology, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane. NMR spectroscopic measurements of xenon adsorption/desorption isotherms and isobars identified a ''breathing effect'' that accompanies a specific volume change.…”

Central-transition double-quantum sideband NMR spectroscopy of half-integer quadrupolar nuclei: estimating internuclear distances and probing clusters within multi-spin networks

“…Yet, during the past decade, several alternatives have been proposed. 15,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] However, these recoupling techniques, a Measurement Science and Standards, National Research Council Canada, including dipolar self-recoupling under MAS 32,33 and experimentation on non-spinning samples, [34][35][36] have predominantly been applied for gaining qualitative information about connectivities, proximities, and distributions of homonuclear spins, or relative orientations of NMR interaction tensors, 15,[17][18][19][22][23][24][25][26][27][28]30,31,[37][38][39][40][41][42][43][44] whereas present reports on direct internuclear distance-estimates remains very sparse. 20,21,45,46 Furthermore, recent work exploits homonuclear through-bond (''J'') interaction...…”

“…[1][2][3][4], whereas much fewer such options exist for half-integer spins. 15,19,22,24,[26][27][28][29][30][31] In ref. 46, we introduced CT 2Q sideband NMR spectroscopy to the realm of half-integer spins: we demonstrated its potential by employing a simple analysis for extracting the internuclear distance in the pair of 11 B spins in bis(catecholato)-diboron (with a relative uncertainty of 2%), in excellent accordance with the value obtained by single crystal X-ray diffraction (XRD).…”

“…26, 27 and 29. While we recommend using the R2 1 2 R2 À1 2 scheme for 2Q CT -excitation in samples displaying relatively low resonance-frequency dispersions, 27,29 the CT 2Q sideband experiment may utilize any 2Q CT generator for half-integer spins, 22,24,[27][28][29][30][31] or supercycles thereof. The pulse trains described in ref.…”