Local inverse photoemission with the scanning tunneling microscope

We have placed photon detectors near the tip-sample region of a scanning tunneling microscope (STM). The intensity of the outcoming photons at various energies was measured as a function of bias voltage between tip and sample. Local inverse-photoemission spectra are presented for polycrystalline tantalum, Si(111)7 × 7, and polycrystalline silver, and are compared to conventional inverse photoemission and tunneling spectroscopy. Some apparent differences are discussed in terms of image/field states. In addition (x,y) scans of the photon intensity demonstrate the potential of this novel technique to combine the spectral resolving power of inverse photoemission with the spatial resolving capabilities of STM. © 1989.