One-dimensional electronic states at surfaces

One-dimensional electron systems can now be synthesized at stepped surfaces by self-assembly of atomic and molecular chains. A wide variety of adsorbate and substrate combinations provides opportunities for systematically tailoring electronic properties, such as the intra-chain and inter-chain coupling, the electron count, magnetic moment and the Coulomb interaction. Angle-resolved photoemission with synchrotron radiation is an ideal probe to reveal the complete set of quantum numbers for electrons at an ordered surface, i.e. energy, momentum parallel to the surface, spin and point group symmetry. Interesting electronic features are discussed, such as spin-charge separation in a Luttinger liquid, charge density waves, the Peierls gap, mixed dimensionality and one-dimensional quantum well states.