STM induced luminescence in carbon nanotubes

Light emission excited by scanning tunnelling microscopy (STM) has been obs erved on multi-wall carbon nanotubes. The photon yield depends on the scann ed tube but it is constant all along the tube. Simultaneous photon spectros copy evidences emitted wavelengths in the 600-1000 nm range in good agreeme nt with previous field emission data. Emission characteristics are independ ent of substrate and of STM tip. We discuss how these new results are consi stent with radiative transitions involving localized states in carbon nanot ubes.