FIGURE 1. Mechanoluminescent spectra from sucrose and resorcinol.

a, Mechanoluminescence of sucrose sonicated in dodecane sparged with N₂ (black trace), crushed in air (green trace), and crushed in N₂-sparged dodecane (red trace), all at 300 K. The emission spectra consist of the N₂(C³_u - B³_g) and N⁺₂(B²⁺_u - X²⁺_g) progressions. The intensity from sonication is an order of magnitude greater than from crushing by hand. b, Mechanoluminescence of resorcinol sonicated in hexadecane (black trace), crushed in air (green trace), crushed in He-sparged hexadecane (red trace) and its photoluminescence (blue trace) at 300 K. Strong helium (He) gas discharge is evident, together with crystal luminescence when resorcinol is sonicated in He-sparged hexadecane; N₂ is emitted because of trace N₂ contamination. No He discharge is detected from grinding in the presence of He gas.