Figure 7

(a) UCL emission spectra of NaYF₄: 40% Mn²⁺/x%Er³⁺ (x% = 1, 2, 5 and 10) nanoparticles and (b) log intensity versus Er³⁺ concentration under 980 nm CW excitation. (c) UCL emission spectra of NaYF₄: 2% Er³⁺/x%Mn²⁺ (x% = 20, 30, 40, 50, 60 and 70) nanoparticles (d) log intensity versus Mn²⁺ concentration under 980 nm CW excitation. (e) UCL emission spectra of NaYF₄: 1% Yb³⁺/40% Mn²⁺/x%Er³⁺ (x% = 0, 2, 5, and 10) nanoparticles (f) log intensity versus Er³⁺ concentration under 980 nm CW excitation. NaYF₄:Yb³⁺/Mn²⁺ nanoparticles emitted relatively strong emission band at 575 nm. The pulse duration for the impact mode was 3 min, the power density of the 980 nm laser was 1 W/cm², and the spot width was 3 mm. 1000 µl of the solution was poured into the cuvette and the cuvette was placed inside the measuring device.