Adsorption of Fluorinated C60 on the Si(111)-(7×7) Surface Studied by Scanning Tunneling Microscopy and High-Resolution Electron Energy Loss Spectroscopy

Abstract

The adsorption structure of fluorinated C60 molecules deposited on the Si(111)-(7×7) surface was studied using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). The results of HREELS revealed the existence of the silicon-fluorine vibration modes with the energy of 103–107 meV, indicating that some of the fluorine atoms were detached from the molecules and chemisorbed to the surface. These fluorine adsorption sites were observed around the adsorbed molecules directly in the STM images. Many of the fluorine-adsorbed sites were found to form thread-like structures. Random formation of the F–Si bonds on the surface prohibits the fluorinated fullerene's freedom from forming an ordered monolayer on the Si(111)-(7×7) surface.