Adsorption of L-Phenylalanine on Cu(001)

Adsorption of phenylalanine on Cu(001) surface was studied by means of scanning tunneling microscopy in ultra high vacuum and has been found to result in only one superstructure, i.e., c(2 x 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 x 4) unit cell, phenyl ring of the molecule is suggested to be oriented nearly perpendicular rather than parallel to the surface. A model thus has been proposed for the c(2 x 4) superstructure, where the π-stacking interactions between neighboring phenyl rings, in addition to hydrogen bond formation, are expected to play an important role in stabilization of the superstructure.