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dc.contributor.authorDe Mello Donegá, C.-
dc.contributor.authorRibeiro, Sidney José Lima-
dc.contributor.authorGonçalves, R. R.-
dc.contributor.authorBlasse, G.-
dc.identifier.citationJournal of Physics and Chemistry of Solids, v. 57, n. 11, p. 1727-1734, 1996.-
dc.description.abstractThe luminescence properties of solid hydrated lanthanide squarates (Ln2(C4O4)3(H2O) x; x = 8 or 13;Ln3+ = Gd, La, Eu, Tb, Pr) are reported for temperatures down to 4.2K. The luminescence of the squarate group is observed for the Gd3+ and La3+ compounds at low temperatures (below 150K). The Pr3+ compound does not show any emission at all, not even at 4.2K. This is ascribed to the quenching of the Pr3+ emission by multiphonon relaxation and/or concentration quenching. The quantum efficiencies of the 5D0 emission of Eu3+ and of the 5D4 emission of Tb3+ in these squarate complexes are strikingly different. Whereas the Tb3+ emission shows a temperature independent quantum efficiency of 50% upon ligand excitation, the Eu3+ emission is strongly quenched, showing a temperature dependent quantum efficiency of 0.8% at 4.2K upon ligand excitation. This quenching is ascribed to the low energy position of the charge-transfer state of Eu3+ in these compounds.en
dc.subjectA. inorganic compounds-
dc.subjectD. luminescence-
dc.subjectD. optical properties-
dc.subjectCharge transfer-
dc.subjectOptical properties-
dc.subjectQuantum efficiency-
dc.subjectConcentration quenching-
dc.subjectLanthanide squarate hydrates-
dc.subjectLigand excitation-
dc.subjectMultiphonon relaxation-
dc.subjectNonradiative processes-
dc.subjectRare earth compounds-
dc.titleLuminescence and non-radiative processes in lanthanide squarate hydratesen
dc.contributor.institutionUniversidade Federal de Pernambuco (UFPE)-
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)-
dc.contributor.institutionDebye Institute-Universiteit Utrecht-
dc.description.affiliationDepto. de Química Fundamental CCEN UFPE, 50,670-901, Recife-PE-
dc.description.affiliationInstituto de Química UNESP, CP 355, 14,800-900, Araraquara, SP-
dc.description.affiliationDebye Institute-Universiteit Utrecht, P.O. Box 80,000, 3508 TA Utrecht-
dc.description.affiliationUnespInstituto de Química UNESP, CP 355, 14,800-900, Araraquara, SP-
dc.rights.accessRightsAcesso restrito-
dc.relation.ispartofJournal of Physics and Chemistry of Solids-
Appears in Collections:Artigos, TCCs, Teses e Dissertações da Unesp

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