MANIPULATION OF ATOMS AND MOLECULES FOR CONSTRUCTION OF NANOSYSTEMS: THE SCANNING TUNNELING MICROSCOPE AS AN OPERATIVE TOOL

Controlled manipulations with scanning tunneling microscope (STM) down to the scale of small molecules and single atoms allow to build molecular and atomic nanosystems, leading to the fascinating possibility of creating manmade structures on atomic scale. Here we present a short review on investigations based on atomic scale manipulation. Upon soft lateral manipulation of adsorbed species, in which only tip/particle forces are used, three different manipulation modes can be discerned: pushing, pulling and sliding. Even the manipulation of strongly bound native substrate atoms is possible. We demonstrate applications as local analytic and synthetic chemistry tools, with important consequences on surface structure research. Vertical manipulation of Xe and CO leads to improved imaging with functionalized tips. With CO deliberately transferred to the tip, we have also succeeded to perform vibrational spectroscopy on single molecules. Furthermore, we describe how we have reproduced a full chemical reaction with single molecules, whereby all basic steps, namely preparation of the reactants, diffusion and association, are induced with the STM tip. Here also field and electron current effects are employed. Finally, we have extended the manipulation techniques to large specially designed molecules by performing lateral manipulation in constant height and realizing the principle of a conformational molecular switch. Artificial nanoscale structures built in atom by atom fashion can serve as quantum laboratories for investigations of various physical properties.