The excitation of one-dimensional plasmons in Si and Au-Si complex atom wires.

An atom-scale quantum wire array at the Au adsorbed Si(111) surface is studied by electron energy loss spectroscopy. Clear one-dimensional metallicity is verified by the observation of low-energy plasmonic excitation which exhibits a strong anisotropic dispersion. Our theoretical analysis using a quantum-mechanical nonlocal response theory shows that the plasmons are most probably supported in conductive channels made of Si honeycomb wires rather than those made of Au-Si complex wires.