Fig. 3.

Optical properties of multicolor mechanoluminescent colloids. (a&b) Excitation (dashed) and emission (solid) spectra of ${\mathrm{S}\mathrm{r}}_2{\mathrm{M}\mathrm{g}\mathrm{S}\mathrm{i}}_2{\mathrm{O}}_7:\mathrm{E}\mathrm{u},\mathrm{D}\mathrm{y}$ (i), ZnS:Cu,Al (ii), ZnS:Mn (iii), and CaTiO₃:Pr (iv) bulk ML materials (a) and their corresponding colloids (b). (c) Schematic showing the setup for mechanoluminescence spectroscopy. (d&e) Mechanoluminescence spectra of ${\mathrm{S}\mathrm{r}}_2{\mathrm{M}\mathrm{g}\mathrm{S}\mathrm{i}}_2{\mathrm{O}}_7:\mathrm{E}\mathrm{u},\mathrm{D}\mathrm{y}$ (i), ZnS:Cu,Al (ii), ZnS:Mn (iii), and CaTiO₃:Pr (iv) bulk materials (d) and their corresponding colloids (e). Data are plotted in colors representative of the emission of corresponding materials.