| Abstract
| - We have investigated the coadsorption of perylene tetracarboxylic dianhydride (PTCDA) and tetraaminobenzene(TAB) on the Ag/Si(111)-√3×√3 R30° surface using scanning tunneling microscopy. At room temperature,PTCDA islands with square and herringbone ordering are formed which, on exposure to TAB, are convertedinto an intermixed phase in which PTCDA and TAB form alternating rows. From our images, we determinethe relative placement of TAB and PTCDA molecules and conclude that the row structure is stabilized byhydrogen bonding between dianhydride and diamine groups. We confirm that this hydrogen bonding junctionis stable using ab initio calculations and show that the proposed geometry is consistent with calculatedintermolecular dimensions.
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