Tb Photophysics: Mapping Excited State Dynamics of [Tb(HO)] Using Molecular Photophysics.

The study of optical transitions in lanthanide(III) ions has evolved separately from molecular photophysics, but the framework still applies to these forbidden transitions. In this study, a detailed photophysical characterization of the [Tb(HO)] aqua ion was performed. The luminescence quantum yield (Φ), excited state lifetime (τ), radiative ( ≡ ) and nonradiative () rate constants, and oscillator strength () were determined for Tb(CFSO) in HO/DO mixtures in order to map the radiative and nonradiative transition probabilities. It was shown that the intense luminescence observed from Tb compared to other Ln ions is not due to a higher transition probability of emission but rather due to a lack of quenching, quantified by quenching to O-H oscillators in the aqua ion of (OH) = 2090 s for terbium and (OH) = 8840 s for europium. In addition, the Horrocks method of determining inner-sphere solvent molecules has been revisited, and it was concluded that the Tb is 9-coordinated in aqueous solution.