Electronic properties of artificial Au chains with individual Pd impurities

Artificial Au atomic chains with individual Pd impurities were assembled from single metal atoms with a scanning tunneling microscope on a NiAl(110) surface. Scanning tunneling spectroscopy (STS) revealed an electronic resonance 2.15 eV above the Fermi energy localized within 4 A of single Pd atom impurities and two electronic resonances 2.25 eV and 2.95 eV above the Fermi energy localized within 8 A of Pd dimer impurities. The emergence of these localized resonances was studied by STS at each stage of the atom-by-atom assembly. Additionally, conductance images of the chains revealed delocalized electronic density oscillations in the pure Au segments of the chains.