Fig. 5From: Revisiting the Enhanced Red Upconversion Emission from a Single β-NaYF4:Yb/Er Microcrystal By Doping with Mn2+ IonsSchematic energy level diagrams for Yb3+, Er3+, and Mn2+ under the 980-nm CW laser excitation, the mechanism of the possible ET, non-radiative transitions, and UC emissions are also presented in the diagramBack to article page