Abstract
The initial adsorption and subsequent Kondo resonance of spin-active 5,10,15,20-tetrakis(4-bromophenyl)porphyrin–Co (TBrPP–Co) molecules on a Si(111)–√3×√3 Ag surface have been studied using low-temperature scanning tunneling microscopy/spectroscopy (STM/S). Different from the case on the Cu(111) surface, all the isolated single TBrPP–Co molecules are anchored in a planar conformation with a slight distortion via their four Br atoms bonding with the Ag atoms of the reconstructed surface structure. The Kondo resonance was also successfully observed above the isolated single molecules adsorbed on the metallic surface. Since the semiconducting Si do not have electronic states at the Fermi level, only the surface state electrons contribute to the observed Kondo resonance.