Ln III Excitation Spectroscopy

For Ln(III) other than Eu(III), the ground state or excited states are non-degenerate. This leads to excitation peaks that are split into multiple components that are quite complex (Fig. 8.2) [17]. It is difficult to deconvolute these peaks if there are multiple species in solution. In contrast, many of the excitation peaks of Eu(III) are relatively simple, especially for those transitions arising from the non-degenerate Fq ground state. Of special simplicity is the Fq transition which falls at 578-581 nm (Fig. 8.3). 

A single peak is observed for each distinct Eu(III) species in solution. This is displayed more clearly in Fig. 8.3 where the Fq Dq excitation peaks of several different Eu(III) complexes are shown both in solution and solid state. In solution, the fiiU width at halfmaximum (FWHM) for each Eu(III) complex is typically around 0.30 nm, but is narrower in the sohd state. The position of the Fq Eu(III) excitation peak has been related to 

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