Paper SS2-ThM1
Thermal Effects of Templated C₆₀ Ordered Structures on AnCA

Thursday, November 12, 2009, 8:00 am, Room N

Anthracene carboxylic acid (AnCA) forms multiphase self-assembly structures on Ag(111). Two of these multiphase structures were employed to investigate the template effects on sequentially deposited C₆₀ molecules using scanning tunneling microscopy. At low C₆₀ coverage, fullerene molecules tend to occupy Ag step edge or AnCA domain boundary sites. With increasing C₆₀ deposition, strong modulation on C₆₀ growth was observed depending on the initially AnCA structures. C₆₀ can either pair into dimers and locate on top of AnCA molecules with the periodicity determined by the underneath AnCA (Interface I), or form small phase-separated C₆₀ and AnCA domains with the width of tens of nanometers (Interface II). Anneal these interfaces at 370 K lead to the desorption of most of the AnCA molecules and the formation of novel C₆₀ structures. For Interface I, the second layer C₆₀ molecules are organized into ordered dimers on top of the first layer zigzag C₆₀ chains running along Ag[1-10] direction. The distance between neighboring zigzag C₆₀ chains is 2 nm, and there are some AnCA molecules left between the zigzag chains to hold the structure stable. For Interface II, parallel C₆₀ chains along Ag[11-2] are observed after annealing. The C₆₀ molecules are close packed along the chain direction and separated by c.a. 1.3 nm between neighboring chains. The molecules have alternative heights across the chain direction, suggesting distinct molecular orientations. Our studies suggest a pathway of nanostructure fabrication through the choice of suitable template and annealing treatment.