Self-assembled monolayers are employed in the fabrication of organic transistors and organic-electronic devices. Polycyclic aromatic hydrocarbons (PAHs), a class of organic precursors made by multiply fused aromatic rings, have been particularly promising for optoelectronics applications. Relatively unexplored is the dynamics of adsorbed PAHs, although the diffusional properties of organic precursors are central in the self-assembly process. The experiments we propose aim to elucidate the dynamics of fluoranthene (a common PAH) on graphite. Previous studies on benzene and pyrene have allowed us to postulate a correlation between molecular size and diffusion rate of PAHs. Our goal now is to verify if the presence of a five-carbon ring in fluoranthene will influence the dynamics of this molecule by making the surface diffusion faster than predicted by the simple molecular-size rule.