Tunneling characteristics at atomic resolution on close-packed metal surfaces

We have observed atomic resolution in constant-current topography along close-packed directions on Cu(111), Au(110) (1x2) and Ag(111) surfaces in UHV. Novel experimental information obtained from tunneling I-V and I-s characteristics observed under "atomic resolution" conditions is presented. Our results are discussed in the light of current theoretical models. We suggest that foreign material in the tip apex plays an important role in the imaging mechanism. © 1992.