Adsorption of L-Phenylalanine on Cu(001)

Adsorption of phenylalanine on a Cu(001) surface was studied by means of scanning tunnelling microscopy in ultrahigh vacuum and has been found to result in only one superstructure, i.e., c (2×4). Moreover, it induces steps faceting to ⟨310⟩ directions and faceted steps bunching to form { 3 1 17} facets. In view of the small size of the c (2×4) unit cell, the phenyl ring of the molecule is suggested to be orientated nearly perpendicular rather than parallel to the surface. A model has thus been proposed for the c (2×4) superstructure, where the π-stacking interactions between neighbouring phenyl rings, in addition to hydrogen bond formation, are expected to play an important role in the stabilization of the superstructure.