Broad Gaussian line shapes were observed in scanning tunneling spectroscopy of single, localized electronic states induced by Cl vacancies in ultra-thin NaCl films on Cu surfaces. Using a simple inelastic resonance tunneling model, it was shown that the observed broad line shapes were caused by a strong coupling between the localized state and the optical phonons in the film. The parameters for the model were obtained from density functional calculations, in which the occupation of the vacancy state temporarily taking place in the experiment has also been accounted for.

Scanning Tunneling Spectroscopy of Cl Vacancies in NaCl Films - Strong Electron-Phonon Coupling in Double-Barrier Tunneling Junctions. J.Repp, G.Meyer, S.Paavilainen, F.E.Olsson, M.Persson: Physical Review Letters, 2005, 95[22], 225503 (3pp)