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. w here Schockley surface-state electrons form. a nearly-free-electron gas. St anding 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-dimension al Fermi contours were visualized by applying the k-space imaging to real s pace views of standing wave oscillations. The origin of the noncircular Fer mi contour will be discussed. (C) 1999 Elsevier Science B.V. All rights res erved.