Transposition hypothesis

So we may consider that in the field of a biology enzymatic system would exist, which could lead from geranyl pyrophosphate to such transpositions. This hypothesis would explain the presence of these compounds into some plants. 

Moreover, the radiative lifetime is not a constant for a given ion and a given electronic level. Indeed, there is a dependence on the refractive index, as clearly shown by eq. (14), so that transposition of a literature value to a specific compound cannot be made directly, which explains the wide range of rrad values reported for an individual Lnm ion. As an example, reported radiative lifetimes for Er111 range from 3 to 12 ms, even for relatively similar compounds (see table 19 below) Another hypothesis inherent to Judd-Ofelt theory is that 4f functions do not contain contributions from 5d orbitals, which is not quite the case for Pr111 and Tbm for instance. Selected data reported in the literature are listed in table 5. 

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