title: Enhanced solid-state NMR correlation spectroscopy of quadrupolar nuclei using dynamic nuclear polarization.
abstract: By means of a true sensitivity enhancement for a solid-state NMR spectroscopy (SSNMR) experiment performed under dynamic nuclear polarization (DNP) conditions, corresponding to 4-5 orders of magnitude of time savings compared with a conventional SSNMR experiment, it is shown that it is possible to record interface-selective (27)Al-(27)Al two-dimensional dipolar correlation spectra on mesoporous alumina, an advanced material with potential industrial applications. The low efficiency of cross-polarization and dipolar recoupling for quadrupolar nuclei is completely negated using this technique. The important presence of pentacoordinated Al has not only been observed, but its role in bridging interfacial tetra- and hexacoordinated Al has been determined. Such structural information, collected at low temperature (∼103 K) and 9.4 T with the use of DNP, would have been impossible to obtain under standard conditions, even using a higher magnetic field. However, here it is demonstrated that this information can be obtained in only 4 h. This work clearly opens a new avenue for the application of SSNMR to quadrupolar nuclei and notably the atomic-scale structure determination of catalysis materials such as mesoporous alumina.
authors.affiliation: Laboratoire de Chimie Inorganique et Biologique, UMR-E CEA/UJF-Grenoble, Institut Nanosciences et Cryogénie, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lee
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Aany S L
authors.initials: AS
authors.lastname: Thankamony
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Dacquin
authors.forename: Michel
authors.initials: M
authors.lastname: Bardet
authors.forename: Olivier
authors.initials: O
authors.lastname: Lafon
authors.forename: Gaël De
authors.initials: GD
authors.lastname: Paëpe
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D016062:Porosity; D012015:Reference Standards; D013499:Surface Properties
chemical_list: D000535:Aluminum; D000537:Aluminum Oxide