There are many reports in the literature of a spectral difference between the triboluminescence (TL) spectrum and the solid-state photoluminescence (PL) spectrum of the same compound. Numerous reasons have been suggested for this difference including pressure-induced changes to Franck-Condon factors during the lifetime of the TL light emission; self-absorption of the TL emission and fracture-induced symmetry changes perturbing the local field of the TL emitting species. However, in a number of cases, the luminescent spectra were recorded on different equipment with different spectral responses, with the resolution of either luminescent spectrum rarely quoted. To avoid artificial spectral differences, care must be taken to account for the response of each equipment over the wavelength range studied, as well as any resolution difference. We have therefore measured the TL and solid-state PL spectra of sixteen TL compounds on the same spectrometer at an identical resolution. Furthermore, the solid-state photoluminescent lifetime has been determined for all samples and the implication that these values have for observing pressure-induced (Franck-Condon) luminescent spectral changes discussed. Finally, in all cases where a significant difference was observed between TL and PL spectra, either self-absorption of the TL emission or fracture-induced perturbations of the local field have been evoked to explain the difference.
- damage sensors