Study of atomistic diffusion, nucleation and cluster formation process of atoms and molecules

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Recently, it is possible to observe atomistic motion of single atoms or single molecules on solid surfaces due to the development of surface probe microscopy, in particular scanning tunneling microscopy (STM). First goal of this study is to understand a cluster formation process from atomistic diffusion of single atoms, just after deposition up to 8 hours. We observed the atomistic motion of Ag atoms on a Si(111)7x7 surface and the formation process of (Ag)n clusters in a 7x7 surface potentials. It is found that the diffusion is cooperative where the hopping rates depend on the nearest neighbor sites. We also measured the tunneling spectroscopy and found that the n=5 and 6 clusters have a specific electronic energy level: Second goal is to investigate the weakest interaction between substrate and the adsorbate atoms or molecules. We observed two -epitaxial structures of pentacene polycrystalline thin film crystals on a hydrogen-terminated Si(111) surface and commensurabilites. Furthermore, we observed the step-induced anisotropic growth of pentacene thin film crystals on a hydrogen-terminated Si(111) surface. In the early stage of this study, we proposed the process for ultra-clean and atomically controlled hydrogen-terminated Si(111)-(1x1) Surface and it is revealed by high resolution electron energy loss spectroscopy, atomic force microscopy and scanning tunneling microscopy. We also propose the deuterium terminated Si(111) surface and observed the surface phonons. Third goal is to investigate the strong interaction between substrate and the adsorbate atoms. Formation process and surface structure of platinum silicide thin layers was studied using STM.Now, we are able to manipulate the single atom or molecule and, then, we try to estimate the cluster size and the electronic structure. Our final goal is to understand the cluster formation process, surface reaction and to form an electronic devices in the atomic scale.