The preserved aromaticity of aniline molecules adsorbed on a Si (5 5 12) -2×1 surface

Abstract

We present a scanning tunneling microscopy and first-principles calculations study of the adsorption structures of aniline on a Si (5 5 12) -2×1 surface. Dissociation from the aniline molecules of one or two H atom(s) bonded to N is favored, and then adsorption onto adatom, tetramer, and dimer rows of Si (5 5 12) -2×1 occurs in several distinct configurations. On the adatom row, aniline binds to an adatom in a tilted configuration, which is formed via a σ bond between the adatom and N, with one dissociated H atom adsorbed on a nearby adatom. No further hydrogen dissociation occurs. On the tetramer and dimer rows, the structures with two dissociated hydrogens and upright configurations are the most stable. Aniline does not adsorb onto the honeycomb chains; this adsorption configuration has a low adsorption energy. In all the adsorption configurations of aniline on this surface, the molecule's aromaticity is preserved. Thus Si-N bonding of aromatic amine molecules provides a strategy for the homogeneous aromatic functionalization of high index Si surfaces. © 2009 American Institute of Physics.