1. Electrical Field-Induced Alignment of Nonpolar Hexabenzocoronene Molecules into Columnar Structures on Highly Oriented Pyrolitic Graphite Investigated by STM and SFM
- Author
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Hans Joachim Räder, Anna Cristadoro, Min Ai, Klaus Müllen, and Jiirgen P. Rabe
- Subjects
Materials science ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Crystallography ,chemistry.chemical_compound ,General Energy ,Adsorption ,Hexabenzocoronene ,chemistry ,law ,Lattice (order) ,Perpendicular ,Molecule ,Graphite ,Scanning Force Microscopy ,Physical and Theoretical Chemistry ,Scanning tunneling microscope - Abstract
Scanning tunneling microscopy (STM) and scanning force microscopy (SFM) have been used to study ultrathin films of a kind of nanographene, hexa(p-n-dodecylphenyl)hexabenzocoronene (HBC-PhC12), on a highly oriented pyrolitic graphite (HOPG) surface. An electrical field, applied parallel to the substrate surface during adsorption from solution and subsequent drying, has been found to align columns of HBC-PhC12 molecules with their long axes perpendicular to the field direction, independently from the HOPG lattice orientation underneath. The molecules, under field influence, adopt a tilted edge-on arrangement on the HOPG surface. On the contrary, the corresponding drop-cast films, dried in the absence of an electrical field, shows a face-on arrangement of the extended aromatic π-system of the HBC-PhC12 discs, and no columnar structures ordered parallel to the graphite surface are recognized. Formation of unidirectionally aligned columns of HBC-PhC12 molecules is, therefore, related to the influence of the el...
- Published
- 2008
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