Atom-resolved surface chemistry using scanning tunneling microscopy

We use scanning tunneling microscopy to investigate the reactivity of the dangling-bond states of Si(111)-(7×7). The reaction with NH3 is used as a prototype. We find that Si rest atoms are more reactive than Si adatoms and that center adatoms are more reactive than corner adatoms. Using atom-resolved electronic spectra, we probe the dangling-bond states on both clean and NH3-exposed surfaces. We find significant interactions and charge transfer between sites which strongly influence surface reactivity. © 1988 The American Physical Society.