The luminescence excitation and emission spectra of the Zn(Tb)S NPs as a function of pH that is modified post-synthetically are shown in panels (a)–(c), respectively. Panel (d) summarizes the relative trend of ZnS and Tb³⁺ emissions in these NPs. The reversible nature of pH dependent effect is shown in panel (e). Panels (f) and (g) show the Tb³⁺ emission lifetime decay profiles and the trends of contributions from shorter-lived surface related and longer-lived core related lifetime components. (Adapted with permission from Reference 108, Copyright 2020 American Chemical Society).