Quantitative analysis of scanning tunneling microscopy images for surface structure determination: sulfur on Re(0001)

Abstract

Scanning Tunneling Microscopy (STM) image of adsorbed atoms and molecules on single crystal substrates provide important information on surface structure and order. In many cases images are interpreted qualitatively based on other information on the system. To obtain quantitative information a theoretical analysis of the STM image is required. A new method of calculating STM images is presented that includes a full description of the STM tip and surface structure. This method is applied to experimental STM images of sulfur adsorbed on Re(0001). The effects of adsorption site, adsorbate geometry, tip composition and tunnel gap resistance on STM image contrast are analyzed. The chemical identity of the tip apex atom and the substrate subsurface structure are both shown to significantly affect STM image contrast.