Triboluminescence with and without Air

Twenty-three triboluminescent organic and inorganic materials were examined for crystal symmetry, differences between photoluminescence and triboluminescence emission spectra, spectroscopic evidence of an electrical discharge, and persistence of activity under liquids; some were also tested under other atmospheres. These experiments indicate that 18 materials were excited by a discharge, by either electron bombardment of the material or secondary excitation by the UV emissions of the surrounding gas. Five are apparently excited without a discharge, probably by the defect recombination characteristic of deformation luminescence.