Scanning tunneling microscopy of electrode surfaces using carbon composite tips

Tips for scanning tunneling microscopy prepared from carbon composite materials were used for nanoscale characterization of highly oriented pyrolytic graphite (HOPG) surfaces, both unmodified and modified with adsorbed monolayers of polyoxometalate. A series of different types of carbon (graphite pencil lead, epoxy sealed carbon fiber, pyrolytic graphite) and polishing/etching steps has been investigated in order to produce sharp tips. Atomic resolution is readily obtained for bare HOPG with these tips and also adsorbed monolayers of polyoxometalates can be characterized at the molecular level. As the graphite tips themselves can be easily modified with monolayers of molecules this opens up applications related to tunneling spectroscopy, scanning electrochemical microscopy or testing of molecular electronic devices.