Fig. 3.

Time-resolved luminescence of ${\mathrm{NaYF}}_4:{\mathrm{Yb}}^{3+}$, ${\mathrm{Er}}^{3+}$ nanoparticles following excitation by a 3 ns laser pulse at 980 nm. (a) Rise and decay of red emission from uncoated particles in dichloromethane. A bin width of 2.048 μs was used. (b) Rise and decay of red emission from lipid coated particles in MES. A bin width of 4.096 μs was used.