STM LIGHT-EMISSION SPECTROSCOPY OF SURFACE MICROSTRUCTURES ON GRANULAR AU FILMS

Light emission spectra from the gap region of a scanning tunneling mic roscope (STM) have been measured simultaneously with the cross-section of the surface topography. The spectra consist of two components cent ered about 1.7 and 2.0 eV. The intensity ratio between these component s varies as the tip moves along different surface structures on the sa mple. We have found a correlation between the light emission spectra a nd the surface topography. We suggest a mechanism that can qualitative ly explain the observed position-dependent spectra.