Figure 1

(a) 10 nm $\times$ 10 nm STM image of the reconstructed Au(100) surface, showing the fringe structure. A conventional $(26\times 5)$ unit cell is drawn in solid lines. (b) Top view of a schematic representation of the hexagonal array of atoms of the overlayer (blue) on the square array of the bulk-terminated Au(100) surface (green). A $(5\times 1)$ unit cell is drawn for reference in purple dashed lines. (c) Detail of the reconstructed overlayer, showing the conventional $(26\times 5)$ unit cell (continuous purple line) and $(13\times 5)$ cells (black dashed line). The fringes direction in (a) and (c) is [110] for the considered domain orientation. (d) LEED pattern of the Au(100) surface taken at 30 eV, showing the two, perpendicular reconstruction domains, one of them predominant. The spots contained in the dashed rectangle are enlarged in the lower side edge. Note the different splitting for each spot.Reuse & Permissions

Figure 2

(a) Fermi surface map of the reconstructed Au(100) measured at h$\nu$ $=$ 41 eV. Experimental data are measured for 180${}^{\circ }$ and symmetrized. Yellow (gray) lines correspond to the surface Brillouin zone edges. Two portions of the Fermi surface are enlarged and shown with enhanced contrast. (b) Theoretical $sp$ band and Shockley surface state are superimposed in green (large circles) and blue/violet (small ovals) solid lines, respectively. Replicas of these states are drawn in dashed lines (not all seen for the photon energy used in this Fermi surface map). Note that the feature detected at $k_x^{\parallel }$ $\simeq$ 0.6 Å${}^{-1}$ is not a replica but due to the cross of the Fermi level by a $sp$ band replica [see (c)]. (c) BE vs $k_{\parallel }$ photoemission spectra along $\left[110\right]$ with the theoretical $sp$ band in green solid line and its replicas in dashed lines at $\pm 2\pi /5a=\pm 0.44$ Å${}^{-1}$. The Shockley surface state is seen at $\overline{\mathrm{X}}$, as well as its replica at $+2\pi /13a$.Reuse & Permissions

Figure 3

Constant energy maps measured with h$\nu$ $=$ 41 eV in areas covering two $\overline{\mathrm{M}}$ points. BEs run from $-0.046$ eV (very close to the Fermi level) to 0.364 eV, below the bottom of the surface state band ($\sim$0.16 eV).Reuse & Permissions

Figure 4

Constant energy maps in the region close to the $\overline{\mathrm{M}}$ point for a large BE range, from $-0.019$ eV to 0.656 eV. Continuous yellow lines highlight the $(1\times 1)$ Brillouin zone edges. For BE values smaller than 0.131 eV, oval shapes, characteristic of the surface state, can readily be seen. In the rest of the panels a number of lines parallel to [110] and $\left[\overline{1}10\right]$ high-symmetry directions (vertical and horizontal in the figure) are observed. In the constant energy map for 0.656 eV, dashed green lines show the shape expected for folding of the bulk $sp$ band in this reciprocal space region at the corresponding BE. The disagreement with the electronic states observed is remarkable.Reuse & Permissions

Figure 5

(a) Intensity cuts at constant $k_y=1.25$ Å${}^{-1}$ obtained from the data of Fig. 4 for different BE values below the bottom of the surface state. Tics mark the position of the intensity maxima in the top curve. (b) Plot of the intensity maxima from panel (a) against their corresponding BE. Red dots correspond to experimental points. The thick dashed line is a linear fit to the data. All other dashed lines are a guide to the eye and obtained by folding with the shown reciprocal lattice vector the thick dashed line. The estimated error bar for experimental points is shown for only one point for clarity. A vertical yellow (gray) line marks the edge of the first Brillouin zone.Reuse & Permissions

Figure 6

Two selected equipotential surfaces extracted from Fig. 4. Panels from (a) to (d) show the nature of the surface state while (e) to (h) explain the behavior of the 1D state. Panel (b) schematic surface state replicas (blue dash lines) while panel (f) is the same, but for the 1D state. These schemes are superimposed in (c) and (g), respectively. Panel (d) shows a schematic view of a 2D free-electron-like surface state in an energy vs parallel momentum representation. Panel (h) shows the same kind of representation for a 1S surface state.Reuse & Permissions