Spatially resolved spectroscopy of gas discharge during sliding friction between diamond and quartz in N2 gas

We performed spectral measurements of gas discharge luminescence caused by triboelectricity during sliding friction between a diamond spherical surface and a quartz plate in N2. As the gas pressure decreased, luminescence of negative glow intensely appeared and vibrational temperature of electronic excited N2 increased. The spatially resolved spectral measurements made it clear that the spectrum of N2 discharge differs from position to position; emission from negative glow was relatively strong on the frictional track where is far from the contact. This result implies that the diamond tip was charged to positive and the frictional track on the quartz to negative. # 2004 Published by Elsevier B.V.