Size- and Site-Dependent Reconstruction in CdSe QDs Evidenced by Se{H} CP-MAS NMR Spectroscopy.
Evidence of size-dependent reconstruction in quantum dots leading to changes in bonding is observed through analysis of the Se{H} cross-polarization magic angle spinning and Se spin-echo solid-state NMR for CdSe quantum dots. The CP-MAS and spin-echo data indicate discrete surface and core Se sites...
| Publicado en: | Journal of the American Chemical Society Vol. 132; no. 10; pp. 3344 - 3355 |
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| Autores principales: | , , , |
| Formato: | Artículo |
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American Chemical Society
3/17/2010
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=48808403&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 48808403 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 3/17/2010 vid: 132 iid: 10 pid: 997 pub: American Chemical Society artinfo: ui: 48808403 10.1021/ja907511r ppf: 3344 ppct: 11 formats: tig: atl: Size- and Site-Dependent Reconstruction in CdSe QDs Evidenced by Se{H} CP-MAS NMR Spectroscopy. aug: au: Derek D. Lovingood Achey, Randall Paravastu, Anant K. Strouse, Geoffrey F. affil: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390 Department of Chemical and Biological Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310-6046 su: Quantum dots Lattice paths Valence (Chemistry) Nuclear magnetic resonance Ramsey theory Structural frame models sug: subj: Quantum dots Lattice paths Valence (Chemistry) Nuclear magnetic resonance Ramsey theory Structural frame models ab: Evidence of size-dependent reconstruction in quantum dots leading to changes in bonding is observed through analysis of the Se{H} cross-polarization magic angle spinning and Se spin-echo solid-state NMR for CdSe quantum dots. The CP-MAS and spin-echo data indicate discrete surface and core Se sites exist with the QD, in which the surface is comprised of numerous reconstructed lattice planes. Due to the nearly 100% enrichment level for Se, efficient spin coupling is observed between the surface Se and sublayer Se sites due to spin diffusion in the CdSe quantum dots. The observed chemical shift for the discrete Se sites can be correlated to the effective mass approximation via the Ramsey expression, indicating a 1/r size dependence for the change in chemical shift with size, while a plot of chemical shift versus the inverse band gap is linear. The-correlation of NMR shift for the discrete sites allows a valence bond theory interpretation of the size-dependent changes in bonding character within the reconstructed QD. The NMR results provide a structural model for the QDs in which global reconstruction occurs below 4 nm in diameter, while an apparent self-limiting reconstruction process occurs above 4 nm. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2010 holdings: @attributes: islocal: N |
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