Atom-resolved surface chemistry studied by scanning tunneling microscopy and spectroscopy.

摘要: We have used scanning tunneling microscopy and spectroscopy to study the reaction of Si(111)- (7×7) with NH3. found that by use topographs obtained at different energies, as well atom-resolved spectra, reacted unreacted surface sites can be imaged selectively. Thus we been able probe spatial distribution on an atom-by-atom basis. find there are significant differences in reactivity between various dangling-bond Si(11l)-(7×7) surface. Specifically, rest-atom more reactive than adatom and, moreover, center-adatom corner-adatom sites. ascribe reduced delocalized nature their state. suggest a bonding interaction adatoms Si atoms directly below them is responsible for this behavior—a suggestion supported electronic-structure calculations. Thus, while site considered saturation process, involves formation hypervalent (fivefold-coordinated) adatom. tentatively center corner strain they induce upon dimer bonds. Atom-resolved allows us interactions charge transfer sites, first time, observe how chemisorption affects substrate electronic structure neighboring