Ultraviolet spectroscopy study of empty electron states of Cu nanoclusters

Abstract

Empty image-potential electron states for Cu nanoclusters on SiO2 have been observed using ultraviolet (UV) light in the energy region of 3.1 eV–6.5 eV. Cu nanoclusters have been formed on the silicon oxide surface, and their size was about 500 nm. In addition to the photoelectron emission from the occupied Shockley surface state, other features have been found in the UV electron spectra. These features are attributed to the direct transition into the image potential states n = 1and 2 from the Shockley surface state and then to the escape from these states into vacuum.