Consistent with the STM results, our ARPES results (see Fig. 2 ) show that the valence bands within the Ag nanowire are strongly anisotropic with a clear band dispersion in the along-wire direction, but no dispersion in the across-wire direction. This strongly suggests that the valence electrons of Ag behave one-dimensionally in the lateral plane (along the wire) and have little interaction with the lattice along the across-wire direction (perpendicular to the wire).
The ARPES studies of this system demonstrate that the electronic structure of the Ag(110) nanowire on Cu(110) considerably deviates from that of bulk Ag band structure in energy dispersion behavior and even in increased energy band number. The most obvious dispersion behavior deviation is that while the photoelectron spectra show dispersion in the vertical (or (110)) and the lateral [¯110] (or along-wire) direction (see Fig. 2. (a) and (b)), they show no dispersion in the lateral  (or across-wire) direction because of the limited dimension of the nanowire width (~ 12 nm in average; see Fig. 2. (c) and (d)). Therefore, the dimensionality of the band structure of the Ag(110) nanowire crystal is reduced in the vertical plane formed by the cross lines parallel to the vertical  and the lateral [¯110] directions. This result is in accordance with the STM results.
The results were presented at the Physical Electronics Conference at Princeton University in June, 2006.
Fig. 2. ( a) Angle-dependent photoelectron spectra from Ag/Cu(110) nanowires (21±5 ML) taken with light beam towards the  direction (along-wire) at photon energy of 16 eV.; ( b) same except with photon beam towards the  direction (across-wire) at photon energy of 16 eV: absence of Ag-d-band dispersion in across-wire direction, contrasting to that of the along-wire direction; (c) Band structure map for the two high-symmetry directions across the (110) surface Brillouin zone, indicating band dispersion in the along-wire direction and absence of dispersion in the across-wire direction. (d) Normal emission photoelectron spectra from the same Ag/Cu(110) nanowires with photon beam towards the along-wire direction ( A ) at photon energy of 14 eV ~ 31 eV
2. The Electronic Structure of Ultra-thin Aluminum Oxide Film Grown on FeAl(110): A Photoemission Spectroscopy
A primary goal of this NSF award is to successfully grow and characterize reduced dimensional metals (1D nanowires and 2D sheets). A strong complementary requisite to realizing this goal is to judiciously develop substrates which, electronically, are relatively inert. The goal of CAMD-LSU researchers, Phil Sprunger and Orhan Kizilkaya, was to grow the proposed nanometals on ultra-thin oxides, wherein, because of the large bandgap, the hybridization/overlap with the underlying substrate band structure is minimized. Ultra-thin oxides serve as excellent templates because they provide a unique “insulating” substrate. Due to the nano-thickness of the oxide, electron spectroscopies (ARPES, STM, EELS) can be used without the problems associated with charging. In order to enable the subsequent growth of reduced-dimensional metals, it is necessary to probe the atomic and electronic structures of the proposed ultra-thin film oxide.