Abstract
Luminescent phenomena during sliding friction between a diamond micro sphere and a flat quartz single-crystal disk under controlled ambient gas pressure of N2, Ar, and Kr were investigated. Spectra of the luminescence clearly indicated the gas discharge of each gas around the frictional contact. Spatial distributions of the gas-discharge luminescence were measured. The distributions at different sliding speeds were almost identical. The distributions depend strongly on the gas species and the pressure; the area of the discharge becomes larger with decrease of the gas pressure.
