Plasma characteristics of the discharge produced during mechanoluminescence

The conditions during light emission from the fracture of solids have been difficult to determine because such mechanoluminescence (ML) is usually weak. When ML is produced by acoustic cavitation of a liquid slurry of resorcinol crystals, however, we observe bright light emission, which makes it possible to measure plasma conditions by emission spectra: a bimodal heavy atom emission temperature profile is observed with 405 +/- 22 K (for 80% of emitting CH) and 4015 +/- 730 K (for 20%), with an electron density and energy of 1.3 +/- 0.13 x 10(14) cm(-3) and similar to 3.5 eV (i.e., an effective T(e) similar to 41 000 K).