Observing the lateral confinement of surface state electrons in room temperature stable metallic nanostructures

The lateral confinement of the surface state electrons of Cu(111) has been studied by Scanning Tunnelling Microscopy and Spectroscopy at low temperature. The confining nanostructures are Cu(111) islands embedded in a semiconducting Cu₃N(111) film which completely isolate them from each other. The standing wave pattern observed reflect the shape of the edge of the islands, i.e. the positions of the confining potential as long as the islands are larger than twice the Fermi wavelength of the surface electrons. The interference pattern in smaller islands is more complex, reflecting the collective behavior of the electrons. When the width of the islands is, at least in one dimension, smaller than the Fermi wavelength, there is a clear shift in the energy of the bottom of the surface band towards the Fermi level. The depopulation of the surface state produced by lateral confinement might have important consequences with respect to the reactivity of these nanostructures.Received: 15 December 2003, Published online: 10 August 2004PACS: 68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM) - 73.20.At Surface states, band structure, electron density of states - 73.22.-f Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals