Zusammenfassung
M₂[Pt(CN)₄]₃•nH₂O compounds (with M³⁺ = Sm³⁺, Eu³⁺, Tb³⁺, ...) represents a new solid state class for investigations of nonradiative excitation energy transfer. The donors are linear stacks (columns) of square planar [Pt(CN)₄]²⁻ complexes and the acceptors are rare earth ions which are located between the stacks. Radiationless energy transfer and sharp line rare earth ion emission have been ...
Zusammenfassung
M₂[Pt(CN)₄]₃•nH₂O compounds (with M³⁺ = Sm³⁺, Eu³⁺, Tb³⁺, ...) represents a new solid state class for investigations of nonradiative excitation energy transfer. The donors are linear stacks (columns) of square planar [Pt(CN)₄]²⁻ complexes and the acceptors are rare earth ions which are located between the stacks. Radiationless energy transfer and sharp line rare earth ion emission have been observed for Sm₂[Pt(CN)₄]₃•18H₂O (SmCP) and Eu₂[Pt(CN)₄]₃•18H₂O (EuCP) but not for Tb₂[Pt(CN)₄]₃•21H₂O (TbCP), although Tb³⁺ generally is a bright emitter. The results are discussed in the scope of the Förster-Dexter theory of resonance energy transfer. It is seen that the spectral overlap integral vanishes for TbCP but not for SmCP nor EuCP. The energy transfer only (or predominantly) occurs from the lower excited state of tetracyanoplatinate stacks. Using emission lifetime data, a transfer rate of 10⁸ - 10⁹ sec⁻¹ is obtained as a lower limit. Such a high rate can only be explained, as an estimate shows, by an exchange transfer mechanism. The spectroscopic properties of the tetracyanoplatinates(II) with and without acceptor ions in the neighborhood are compared.
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