| AVS 59th Annual International Symposium and Exhibition | |
| Tribology Focus Topic | Tuesday Sessions |
| Session TR-TuP |
| Session: | Tribology Poster Session |
| Presenter: | I. Arakawa, Gakushuin University, Japan |
| Authors: | T. Miura, National Institute of Occupational Safety and Health, Japan E. Imai, Gakushuin University, Japan I. Arakawa, Gakushuin University, Japan |
| Correspondent: | Click to Email |
The origin of triboluminescence of solid in air has been believed to be essentially photoluminescence excited by ultraviolet light from nitrogen discharge caused by triboelectricity (see Walton's review, Adv. Phys. Vol. 26 (1977) p.919.). In this study, we propose that electron-impact is a major and significant origin of the solid luminescence.
The experiment of friction between quartz and diamond was performed in rare gases or nitrogen by a pin-on-disk equipment in a vacuum chamber. A spatial distribution of the triboluminescence was observed by a microscope through the quartz disk and its spectrum was measured by a spectrometer.
Typical discrete lines due to the light emission of the gas discharge and a broad band (wavelengths of 300-600 nm) were observed in the triboluminescence spectrum. The microscopic measurement made it clear that the gas discharge occurred in a gap between quartz and diamond around the contact point and the broad band was emitted at the same place of the gas discharge.
By changing the gas pressure, however, we found that the discharge light almost vanished in the pressure range of 30-100 Pa of nitrogen, while the broad band emission intensely appeared in this range. The broad band intensity became a maximum when a mean free path of electron in plasma was close to the gap distance of the discharge.
It has been known that the quartz was negatively electrified by friction with diamond. We have performed cathode-luminescence experiment for the same diamond sample. A broad band appeared in the spectrum of the cathode-luminescence was identical to the broad band of the triboluminescence.
In conclusion, gas discharge caused by triboelectricity induces cathode-luminescence of the solid. This is the main cause of the broad band in the triboluminescence. Contribution of the ultraviolet light of the nitrogen discharge to the solid luminescence, in contrast, is negligible.