Observation of two-dimensional Fermi contour of a reconstructed Au(111) surface using Fourier transform scanning tunneling microscopy

Applying a two-dimensional fast Fourier transform to a real space image of scanning tunneling microscopy, visualization of a complementary image in k space can be realized for an Au(111)-(22 x root 3) reconstructed surface. where Schockley surface-state electrons form. a nearly-free-electron gas. Standing waves in the surface local density of states modulated by the large-scale herringbone reconstruction were observed in the vicinity of monolayer steps at 30 K using extremely low bias voltages. Noncircular two-dimensional Fermi contours were visualized by applying the k-space imaging to real space views of standing wave oscillations. The origin of the noncircular Fermi contour will be discussed. (C) 1999 Elsevier Science B.V. All rights reserved.