Dependence of spontaneous emission rates of emitters on the refractive index of the surrounding medial

For emitters in a medium, different macroscopic or microscopic theoretical models predict substantially different dependencies of the spontaneous emission lifetime on refractive index. Various measurements have been carried out on Eu$^{3+}$, Ce$^{3+}$ and Nd$^{3+}$ ions, and quantum dots in different surrounding medial. The dependence of the spontaneous emission rates on refractive index has been interpreted with different models. By closely examining some of the experimental results, we notice that some interpretations are based on implicit assumptions which are hard to justify, and some measurements contain too big uncertainties to discriminate among different models. In this work we reanalyse the avilable measured results and give a consistent interpretation.