abstract
In many EuIII-based materials, the presence of an intermediate energy level, such as ligand-to-metal charge transfer (LMCT) states or defects, that mediates the energy transfer mechanisms can strongly affect the lifetime of the 5D0 state, mainly at near-resonance (large transfer rates). We present results for the dependence of the 5D0 lifetime on the excitation wavelength for a wide class of EuIII-based compounds: ionic salts, polyoxometalates (POMs), core/shell inorganic nanoparticles (NPs) and nanotubes, coordination polymers, beta-diketonate complexes, organicinorganic hybrids, macro-mesocellular foams, functionalized mesoporous silica, and layered double hydroxides (LDHs). This yet unexplained behavior is successfully modelled by a coupled set of rate equations with seven states, in which the wavelength dependence is simulated by varying the intramolecular energy transfer rates. In addition, the simulations of the rate equations for four- and three-level systems show a strong dependence of the emission lifetime upon the excitation wavelength if near-resonant non-radiative energy transfer processes are present, indicating that the proposed scheme can be generalized to other trivalent lanthanide ions, as observed for TbIII/CeIII. Finally, the proper use of lifetime definition in the presence of energy transfer is emphasized.
keywords
EUROPIUM(III) MIXED COMPLEXES; ORGANIC-INORGANIC HYBRIDS; QUANTUM YIELDS; COORDINATION-COMPOUNDS; THEORETICAL APPROACH; O-PHENANTHROLINE; LANTHANIDE IONS; BETA-DIKETONES; UP-CONVERSION; LUMINESCENT
subject category
Chemistry
authors
Ferreira, RAS; Nolasco, M; Roma, AC; Longo, RL; Malta, OL; Carlos, LD
our authors
Luís Carlos
Full professor
Maria Rute de Amorim e Sá Ferreira André
Full professor
Mariela Martins Nolasco
Assistant ResearcherGroups
G2 - Photonic, Electronic and Magnetic Materials
G6 - Virtual Materials and Artificial Intelligence
Projects
acknowledgements
The authors are grateful to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), COMPETE and FEDER programs (Pest-C/CTM/LA0011/2011, PTDC/CTM/101324/2008), CNPq, CAPES, PRONEX-FACEPE-CNPq (APQ-0859-1.06/08) and INCT INAMI (Brazil) for financial support. LDC thanks the Nanobiotec-CAPES network for a grant, and the authors acknowledge P. Tanner, City University of Hong Kong, for the tests performed on the wavelength dependence of the 5D