Praseodymium selective fluorescence recognition based on GdPO₄: Tb³⁺ probe via energy transfer from Tb³⁺ to Pr³⁺ ions

A novel strategy is proposed based on the efficient energy transfer from Tb³⁺ to Pr³⁺ for the sensitive and selective discrimination of praseodymium ions due to the matched energy levels of ⁵D₄ (Tb³⁺) and ³P₀ (Pr³⁺). The electron of Tb³⁺ transfers from the ground state to the excited state under the excitation of ultraviolet light and relaxes to the ⁵D₄ level. In the presence of Pr³⁺ the electron has no time to return to the ground state, thus it transfers to the ³P₀ level of Pr³⁺ resulting in the quenching of Tb³⁺ luminescence. In the case of GdPO₄: Tb³⁺ nanowire, its fluorescence intensity at 545 nm linearly decreased when Pr³⁺ concentration ranged from 1 × 10^-7 to 1 × 10^-5 M, and the detection limit was 75 nM. To further investigate the sensing mechanism, CePO₄: Tb³⁺, YPO₄: Tb³⁺, and YBO₃: Tb³⁺ nanoparticles were also synthesized for Pr³⁺ ion detection. For all materials, similar fluorescence quenching by Pr³⁺ ions occurred, which confirmed the efficient energy transfer from Tb³⁺ to Pr³⁺ ions. Utilizing the matched energy levels of ⁵D₄ (Tb³⁺) and ³P₀ (Pr³⁺), for the first time, we proposed a novel strategy (taking GdPO₄: Tb³⁺ probe as the example) based on the efficient energy transfer from Tb³⁺ to Pr³⁺ for the sensitive and selective discrimination of praseodymium ions.