Fig. 1. "Star" on the surface of graphite
Scientific and Production Enterprise "Center for Advanced Technologies" has developed a new nanolithography method for carbon materials, which is in the anodic oxidation of the surface with a probe of an atomic force microscope. With the probe nanolithography method can be found in the master-class. It was held by the center staff at the conference at the Moscow State University named after MV Lomonosov.
Probe methods in which to study the surface used atomic-sharp needles (probes), has recently received increased attention. In nanoworld probes like fingers can touch the separate atoms. Modern instruments can accurately track the movement of nanoscale probe moving along the surface, repeating the relief of atomic structures. Thus are born the fascinating images of the nanoworld. Fig. 1 shows a "star" on the graphite surface, the thickness of the petals which is only 5 carbon atoms.
High spatial resolution in scanning probe microscopy achieved due to the small area of interaction between the atoms on the tip of the probe and the surface. In contrast to optical microscopy, the diffraction limit is not a barrier.
Fig. 2. The scanning probe microscope "FemtoScan." Despite its compact size, it allows you to implement more than 50 methods of scanning probe microscopy, and in the working conditions in the air provides atomic resolution
Scanning can be performed in different environments — and even the air in the liquid. In many cases, does not require expensive vacuum equipment — as in electron and ion microscopy. Probe microscopes have a compact and easy to integrate with other devices (see Fig. 2). All this gives the researcher more opportunities. For example, the molecules of the surrounding area can be made to react with the surface atoms. For this purpose between the probe and the surface voltage is applied, the surface is positively charged — the regime of local anodic oxidation (LAO). In an electrochemical reaction surface atoms are oxidized to form oxides.
If the carbonaceous material is subjected to oxidation, the pits are formed by the probe as carbon oxides (CO and CO2) gaseous. Initially it was assumed that carbon atoms react with oxygen. However, subsequent experiments showed that the main oxidant, in this case — the water is condensed from the air onto the surface.
Recently it was found that the oxidation of graphite can be formed as pits and lumps. Increasing the height of the surface to explain the formation of graphite oxide. This compound retains a layered structure of graphite, but the layers of carbon atoms due to the curved attachment oxygen chemical groups. Also, is the introduction of water molecules in the interlayer space, which explains the appearance of bumps on the surface. In contrast to graphite, an oxide dielectric is therefore by local oxidation of the surface may be graphite nanostructure created various electronic devices, chemical and biological sensors, pads for experiments with single living cells. The method allows for only a few minutes to form nanostructures with a resolution down to 10 nm.
Fig. 3. Nanozverey traces on the surface of graphite. Figure created by local anodic oxidation
The unique method of conquering the hearts not only a nano-engineer, but also people with a craving for beauty. Increasingly, artists are turning to technology to implement their ideas. During the short time of a master-class in nanolithography on a graphite surface appeared herds nanoenotov nanozverey and traces (see Fig. 3). It turned out that one piece of graphite with a side of 1 cm provides unlimited opportunities for creativity, and it can be placed up to 100 million micron films.