Enhancement of signal intensity for inverse photoelectron spectroscopy by surface plasmon resonance in the near-ultraviolet range

Abstract

The unoccupied states of solids can be directly examined by inverse photoelectron spectroscopy (IPES). The fundamental drawback of IPES is its low signal intensity. Although the intensity of the IPES signal may be enhanced by surface plasmon resonance (SPR), however, with conventional IPES this was impossible because the photon energy involved in this techinique is much higher than the SPR energy of existing materials. In 2012, we developed a low-energy IPES (LEIPS), in which the photon energy is lowered to less than 5 eV. Thus the photon energy of the IPES can be matched with the SPR energy. We demonstrate the enhancements of the LEIPS signal of Ag and organic semiconductors by the SPR of Ag nanoparticles.