Quasi-epitaxy of a tris(thieno)hexaazatriphenylene derivative adsorbed on Ag(110): Structural and electronic properties probed by scanning tunneling microscopy

Scanning tunneling microscopy is used to study the structure of monolayers of tris{2,5-bis(3,5-bis-trifluoromethyl-phenyl)-thieno}[3,4-b,h,n]-1,4,5,8,9,12- hexaaza-triphenylene adsorbed on a clean Ag(110) single-crystal surface. The molecules adsorb flat on the surface, forming two-dimensional islands within which intermolecular interactions constrain the molecules to form rows of molecular pairs. The balance between intermolecular and molecule-substrate interactions leads to two specific orientations of these rows at +11° and -11° from the [001] direction of the Ag(110) surface. A comparison between observed and calculated local densities of states shows an antiparallel azimuthal orientation of the molecules within the closely associated pairs. The structure of the full monolayer shows that the intermolecular interaction overcomes the interaction with the substrate, resulting in a reorientation of the rows along various directions.