INDEX triplet lifetimes

The observed hfetime usually significantly depends on the temperature (whereas the radiative lifetime only depends on the small variation of the retractive index as a function of temperature if the coordination is unaffected by the lower temperature). This dependence comes from the fact that some nonradiative deactivations of the lanthanide ion are vibrationally assisted (i.e., needs some heat to take place, e.g., back-transfer to the triplet state of the ligand). Nevertheless, the observed lifetime of the lanthanide does not depend on the excitation wavelength. A direct excitation through an f-f transition or through a sensitizer results in the same observed lifetime. In other words, this hfetime, and thus the deactivation of the lanthanide excited state only depends on the chemical environment and on the temperature, not on how this excitation was achieved. 

There have been several reviews of mechanisms of photosubstitution in rhodium(III) complexes. Bond indexes for ground and excited states have been discussed in relation to D2h species. " The observation of stereospecificity has been discussed in relation to lifetimes for triplet singlet deactivation and geometric rearrangements. Direct evidence has been presented to support the intermediacy of, and role of rearrangement in, five-coordinate intermediates in ligand field irradiation experiments. Rhodium(III) has been discussed in relation to cobalt(III) and iridium(III), and to ruthenium(II) and ruthenium(III) as well. ... 

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