Light emission has been detected at the tip-sample junction of a Scanning Tunneling Microscope (S.T.M.) in air on noble metallic surfaces. A spectroscopic study of emitted photons for Au-Au and Ptlr-Au tunneling junctions is presented. The general aspect of the spectra depends on the materials used in the junctions; a study of the spectra as a function of tunneling current and surface bias volt...
