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Energy-transfer mechanisms and emission quantum yields in Eu3+-based siloxane-poly(oxyethylene) nanohybrids

dc.contributor.authorFerreira, RAS
dc.contributor.authorCarlos, L. D.
dc.contributor.authorGoncalves, R. R.
dc.contributor.authorRibeiro, SJL
dc.contributor.authorBermudez, V. D.
dc.contributor.institutionUniv Aveiro
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniv Tras Os Montes & Alto Douro
dc.date.accessioned2014-05-20T15:22:18Z
dc.date.available2014-05-20T15:22:18Z
dc.date.issued2001-09-01
dc.description.abstractWe report the energy-transfer mechanisms and emission quantum yield measurements of sol-gel-derived Eu3+-based nanohybrids. The matrix of these materials, classified as diureasils and termed U(2000) and U(600), includes urea cross-links between a siliceous backbone and polyether-based segments of two molecular weights, 2000 and 600, respectively. These materials are full-color emitters in which the Eu3+ (5)Do --> F-7(0-4) lines merge with the broad green-blue emission of the nanoscopic matrix's backbone. The excitation spectra show the presence of a large broad band (similar to 27000-29000 cm(-1)) undoubtedly assigned to a ligand-to-metal charge-transfer state. Emission quantum yields range from 2% to 13.0% depending on the polymer molecular weight and Eu3+ concentration. Energy transfer between the hybrid hosts and the cations arises from two different and independent processes: the charge-transfer band and energy transfer from the hybrid's emitting centers. The activation of the latter mechanisms induces a decrease in the emission quantum yields (relative to undoped nanohybrids) and permits a fine-tuning of the emission chromaticity across the Comission Internacionalle d'Eclairage diagram, e.g., (x, y) color coordinates from (0.21, 0.24) to (0.39, 0.36). Moreover, that activation depends noticeably on the ion local coordination. For the diureasils with longer polymer chains, energy transfer occurs as the Eu3+ coordination involves the carbonyl-type oxygen atoms of the urea bridges, which are located near the hybrid's host emitting centers. on the contrary, in the U(600)-based diureasils, the Eu3+ ions are coordinated to the polymer chains, and therefore, the distance between the hybrid's emitting centers and the metal ions is large enough to allow efficient energy-transfer mechanisms.en
dc.description.affiliationUniv Aveiro, Dept Fis, P-3810193 Aveiro, Portugal
dc.description.affiliationUNESP, Inst Quim, BR-14801970 Araraquara, SP, Brazil
dc.description.affiliationUniv Tras Os Montes & Alto Douro, Dept Quim, P-5001911 Vila Real, Portugal
dc.description.affiliationUnespUNESP, Inst Quim, BR-14801970 Araraquara, SP, Brazil
dc.format.extent2991-2998
dc.identifierhttp://dx.doi.org/10.1021/cm010311o
dc.identifier.citationChemistry of Materials. Washington: Amer Chemical Soc, v. 13, n. 9, p. 2991-2998, 2001.
dc.identifier.doi10.1021/cm010311o
dc.identifier.issn0897-4756
dc.identifier.urihttp://hdl.handle.net/11449/33313
dc.identifier.wosWOS:000171104200040
dc.language.isoeng
dc.publisherAmer Chemical Soc
dc.relation.ispartofChemistry of Materials
dc.relation.ispartofjcr9.890
dc.relation.ispartofsjr4,675
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleEnergy-transfer mechanisms and emission quantum yields in Eu3+-based siloxane-poly(oxyethylene) nanohybridsen
dc.typeArtigo
dcterms.licensehttp://pubs.acs.org/paragonplus/copyright/jpa_form_a.pdf
dcterms.rightsHolderAmer Chemical Soc
unesp.author.orcid0000-0002-8162-6747[4]
unesp.author.orcid0000-0001-5540-7690[3]
unesp.author.orcid0000-0003-4747-6535[2]
unesp.author.orcid0000-0002-7577-4938[5]
unesp.author.orcid0000-0003-1085-7836[1]

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