We investigate the fluorescence dynamics of the rare-earth ions europium, terbium, and gadolinium, with particular emphasis on quantifying non-Markovian behavior. By employing fluorescence as a probe, we characterize deviations from memoryless dynamics and identify clear distinctions between Markovian and non-Markovian regimes. Our analysis demonstrates how these profiles manifest in optical spectroscopy, providing direct insight into system–environment interactions. Beyond their fundamental implications, these insights may support the rational design of rare-earth-doped materials for applications in multicolor phosphors, hybrid optoelectronic architectures, and emerging quantum sensing technologies.
Triviño et al. (Thu,) studied this question.