Cutoff anomalies in light emitted from the tunneling junction of a scanning tunneling microscope in air

Light emission from noble metal tunneling junctions of a scanning tunneling microscope has been detected in air. A spectroscopic study of the photons emitted from Au/Au and PtIr/Au junctions has been performed as a function of the applied bias voltage. A higher-energy emission band, which grows in as a function of bias voltage, has been observed in the recorded spectra. The high energy cutoffs of the recorded spectra do not follow the quantum law hνcutoff=eVsample.