Triboluminescence of trans-stilbene, p-terphenyl and polycyclic aromatic hydrocarbons

Abstract The luminescence of trans-stilbene, p-terphenyl and polycyclic aromatic hydrocarbons (PAHs) during the mechanical grinding of microcrystals in a working cell is studied. The triboluminescence of trans-stilbene, p-terphenyl, naphthalene, anthracene, pyrene, and coronene was detected. No triboluminescence spectrum of tetracene was recorded because of low intensity. No gas component of a triboluminescence spectrum (the lines of N2 molecules and atoms of inert gases) was recorded for all polyaromatic hydrocarbons in air and inert gases (Ne, Ar, and Kr). The bands coinciding with fluorescence spectra of trans-stilbene, p-terphenyl, naphthalene, and anthracene are observed in their triboluminescence spectra during the mechanical grinding of their crystals. High-intensity luminescence of excimers is observed in the triboluminescence spectrum of pyrene and coronene, and there is no luminescence of their monomers. Stable triboluminescence of a pyrene monomer, however, is observed during the grinding of a 200:1 naphthalene/pyrene microcrystal mixture, and it appeared due to the transfer of excitation energy from a naphthalene molecule to pyrene one. The triboluminescence of tetracene was also detected in an anthracene/tetracene mixture. A mechanism of triboluminescence of trans-stilbene, p-terphenyl and PAHs is proposed as electroluminescence arising due to recombination of charge carriers in the electric field of a crystalline layer electrified during the grinding.