Directed self-assembly to create molecular terraces with molecularly sharpboundaries in organic monolayers

We demonstrate the ability to control the placement of molecules within sel f-assembled films. We show quasi-two-dimensional mosaic structures within t wo-component self-assembled monolayers. These demonstrate new types of mono layer features: the domains of each component form molecular terraces, and the boundaries between these domains form molecular step edges. We find the molecular step edges are molecularly sharp and laterally epitaxial. The mo lecular step edges have the unique ability to expose a typically buried par t of the larger molecule at the boundary. For the identical components in t he crystalline monolayer, we can also distribute the molecules randomly. Th ese structures were selected and created using simple controlled sequences of self-assembly and processing with different length alkanethiols on Au{11 1}. We have imaged these films using molecular resolution scanning tunnelin g microscopy.