Strongly anisotropic band dispersion of an image state located above metallic nanowires

Indium can be grown on Si(111) in a 4 x I pattern that contains rows of In atoms spaced 13.3 Angstrom apart that have quasi-one-dimensional electronic structure. This ordered array of metallic wires produces an image-induced surface state series. We have measured the dispersion of the most tightly b ound (n = 1) image state band and found it to be unconventional because it falls below the free electron parabola perpendicular to the In atom rows. T he most straightforward explanation for this is that the electrons feel the surface corrugation potential produced by the rows of In atoms. We were ab le to infer the form of the potential from our measurements.