Mechanoluminescence: light from sonication of crystal slurries.

Mechanoluminescence, also known as triboluminescence or fractoluminescence, is light emission induced as a result of mechanical action on a solid--for example, Francis Bacon noted as long ago as 1605 that lumps of sugar emitted light when scraped. Here we elicit mechanoluminescence by a new means, acoustic cavitation, and find intense luminescence and emission lines that are not generated by other mechanisms such as grinding, cleaving, rubbing, scratching, biting or thermal shock.