Fig. 4From: Revisiting the Enhanced Red Upconversion Emission from a Single β-NaYF4:Yb/Er Microcrystal By Doping with Mn2+ IonsThe UC emission intensity ratios for a single β-NaYF4:Yb/Er (20/2 mol%) microcrystal doping with different concentrations of Mn2+ ions under the excitation intensity of (a) 1.59 kW cm−2 and (b) 95.52 kW cm−2Back to article page