Emission Efficiency and Rate Constants

The emission efficiency is given by the quantum yield of luminescence (p, which is simply the ratio of emitted photons, to photons absorbed by the sample, p bs, as shown in Equation 1.75. 

In the case of lanthanides, foUowing direct excitation of the metal ion, the efficiency of emission is called the intrinsic emission efficiency which is directly related to the overall rate at which the emissive state is depopulated through radiative/ and non-radiative NR pathways, and the radiative rate constant, k/, or their corresponding 

The experimentally observed excited state lifetime reflects the contribution of all processes, which lead to the deactivation of the excited state, both radiative and non-radiative. 

Equation 1.72 above relates the radiative lifetime to the magnetic dipole-allowed transition of Eu(III). It is therefore straightforward to determine experimentally, for this ion, tr and therefore the intrinsic emission efficiency. 

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