C-REDOR curves of extended spin systems

Celinski, Vinicius R.; Weber, Johannes; Günne, Jörn Schmedt auf der

doi:10.1016/j.ssnmr.2012.10.001

Cited by 12 publications

(14 citation statements)

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“…The sparse density of hydrogens in hydromagnesite and other minerals diminishes such 1 H– 1 H influence and offers a unique opportunity to probe 13 C– 1 H interactions. This hydromagnesite study is one of only a few examples–from a search of the literature, we found only 16 reports of 1 H‐dephased REDOR, and only 4 of those are between 1 H and 13 C …”

Section: Figurementioning

confidence: 94%

“…[43,44] Dipolar coupling from 13 Cto 1 His normally complicated to measure as protons are typically strongly coupled to each other via homonuclear dipole-dipole interactions.T he sparse density of hydrogens in hydromagnesite and other minerals diminishes such 1 H-1 Hi nfluence and offers aunique opportunity to probe 13 C-1 Hinteractions. This hydromagnesite study is one of only af ew examplesfrom asearch of the literature,wefound only 16 reports of 1 Hdephased REDOR, and only 4o ft hose are between 1 Ha nd 13 C. [45][46][47][48] DFT is widely used to study structure,b onding and properties of solids. [49] DFT calculations based on generalized-gradient approximation (GGA) [50] exchange-correlation functionals have been widely applied and demonstrated to yield high accuracy for aw ide variety of materials systems, displaying ar ange of bonding types.…”

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confidence: 99%

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NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

et al. 2019

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Solid‐state NMR measurements coupled with density functional theory (DFT) calculations demonstrate how hydrogen positions can be refined in a crystalline system. The precision afforded by rotational‐echo double‐resonance (REDOR) NMR to interrogate 13C–1H distances is exploited along with DFT determinations of the 13C tensor of carbonates (CO32−). Nearby 1H nuclei perturb the axial symmetry of the carbonate sites in the hydrated carbonate mineral, hydromagnesite [4 MgCO3⋅Mg(OH)2⋅4 H2O]. A match between the calculated structure and solid‐state NMR was found by testing multiple semi‐local and dispersion‐corrected DFT functionals and applying them to optimize atom positions, starting from X‐ray diffraction (XRD)‐determined atomic coordinates. This was validated by comparing calculated to experimental 13C{1H} REDOR and 13C chemical shift anisotropy (CSA) tensor values. The results show that the combination of solid‐state NMR, XRD, and DFT can improve structure refinement for hydrated materials.

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confidence: 94%

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confidence: 99%

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

et al. 2019

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“…Spectra deconvolution was done with deconv2Dxy . The statistical and heterogeneous errors in the REDOR plot were calculated using the method reported in ref .…”

Section: Experimental Sectionmentioning

confidence: 99%

Thermal Hardening and Defects in Anodic Aluminum Oxide Obtained in Oxalic Acid: Implications for the Template Synthesis of Low-Dimensional Nanostructures

Aman

Wied

Alhusaini

et al. 2019

ACS Appl. Nano Mater.

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This study addresses the investigation of the nature of defects generated during the anodization of aluminum using oxalic acid electrolyte and their influence on the structure and properties of anodic aluminum oxide films (AAO). AAO films, which are obtained by anodization in oxalic acid, and their powdered samples are subjected to thermal annealing at temperatures up to 1050 °C and are subsequently investigated by 27 Al solid-state nuclear magnetic resonance (NMR), electron spin resonance (ESR), powder X-ray diffraction, scanning electron microscopy (SEM), and nanoindentation. By NMR and continuous wave ESR, it is found that the anodization obtained in oxalic acid not only produces amorphous porous alumina, but also gives rise to bulk H defects and unpaired electrons originating from the decomposition of the oxalate ions. Paramagnetic defects are healed by annealing at temperatures of ∼800 °C in air, possibly by an oxidative conversion to CO 2 with the oxygen in air, while the removal of the H defects requires temperatures of at least 1050 °C. The observed hardening of the films and color changes can be explained by changes in structure on an atomic scale and changes in composition: amorphous AAO is converted to a poorly crystalline intermediate phase containing η-Al 2 O 3 at ∼800 °C and subsequently to crystalline α-Al 2 O 3 (corundum) at ∼1050 °C. Moreover, thermal hardening of an AAO passivation layer on top of metallic aluminum with the flame of a H 2 /O 2 burner was demonstrated.

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“…The sparse density of hydrogens in hydromagnesite and other minerals diminishes such 1 H-1 H influence and offers a unique opportunity to probe 13 C-1 H interactions. This hydromagnesite study is one of only a few examples--from a search of the literature, we have only found 16 reports of 1 H-dephased REDOR, and only 4 of those are between 1 H and 13 C. [45][46][47][48] DFT is widely used to study structure, bonding and properties of solids. [49] DFT calculations based on generalized-gradient approximation (GGA) [50] exchange-correlation functionals have been widely applied and demonstrated to yield high accuracy for a wide variety of materials systems, displaying a range of bonding types.…”

mentioning

confidence: 99%

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

et al. 2019

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C-REDOR curves of extended spin systems

Cited by 12 publications

References 78 publications

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

Thermal Hardening and Defects in Anodic Aluminum Oxide Obtained in Oxalic Acid: Implications for the Template Synthesis of Low-Dimensional Nanostructures

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

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C-REDOR curves of extended spin systems

Cited by 12 publications

References 78 publications

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by 13C{1H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by 13C{1H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

Thermal Hardening and Defects in Anodic Aluminum Oxide Obtained in Oxalic Acid: Implications for the Template Synthesis of Low-Dimensional Nanostructures

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by 13C{1H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

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NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors

NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by ¹³C{¹H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors