A_rel: Investigating [Eu(H₂O)₉]³⁺ Photophysics and Creating a Method to Bypass Luminescence Quantum Yield Determinations

Abstract

Lanthanide luminescence has been treated separate from molecular photophysics, although the underlying phenomena are the same. As the optical transitions observed in the trivalent lanthanide ions are forbidden, they do belong to the group that molecular photophysics has yet to conquer, yet the experimental descriptors remain valid. Herein, the luminescence quantum yields (ϕ lum ), luminescence lifetimes (τ obs ), oscillator strengths (f), and the rates of nonradiative (k nr ) and radiative (k r ≡ A) deactivation of [Eu(H 2 O) 9 ] 3+ were determined. Further, it was shown that instead of a full photophysical characterization, it is possible to relate changes in transition probabilities to the relative parameter A rel , which does not require reference data. While A rel does not afford comparisons between experiments, it resolves emission intensity changes due to emitter properties from intensity changes due to environmental effects and differences in the number of photons absorbed. When working with fluorescence this may seem trivial; when working with lanthanide luminescence it is not.

We are never ever getting (back to) ideal symmetry: structure and luminescence in a ten-coordinated europium(iii) sulfate crystal

“…The radiative rate constant of Eu(O) 10 in the crystal was determined as k r = 160 s −1 . Compared to the highly symmetric nine-coordinated europium aqua ion, with a k r = 116 ± 2 s −1 in solution, 24 and already having taken the higher refractive index of the crystal into account, we must conclude that the transition probability of Eu( iii ) in Eu(O) 10 in the crystal is significantly higher. This indicates an overall lower symmetry environment for Eu( iii ) in the crystal than that for the non-aqua coordinated Eu( iii ) in solution.…”

Long story short: donor set symmetry in [Eu(DOTA)(H2O)]−crystals determines the electronic structure

“…All four spectra show a single line in the 5 D 0 to 7 F 0 band at 580 nm, clearly indicating that only one species is present. 31,51 Even so the differences are clear.…”

Long Story Short: Donor Set Symmetry in Eu(DOTA) Crystals Determines the Electronic Structure

“…All four spectra show a single line in the 5 D0 to 7 F0 band at 580 nm, clearly indicating that only one species is present. 31,50 Even so the differences are clear.…”