Nanotechnology microscopes

For each technique, the calibration phase and the comparison of preliminary results with standard measurements are fundamental. They ensure that subsequent analyses can be performed with a high reliability level. The evaluation of results is very difficult in nanotechnological microscopic analysis. In fact, the reduced size of samples, together with the complexity of the instruments and physical and chemical phenomena occurring in nanoscale dimensions (e.g. relativistic effects), introduces numerous stochastic variables, making measurement and relative analysis very complex, with complicated evaluation and interpretation of results. 

Maivald, P, Butt, H.J., Gould, S.A., Prater, C.B., Drake, B., Gurley, J.A., Elings, VB. and Hansma, P.K.. Using force modulation to image surface elasticities with the atomic force microscope. Nanotechnology, 2, 103-106 (1991). 

The twenty-first century demands novel materials of the scientist. New instruments have made possible the field of nanotechnology, in which chemists study particles between 1 and 100 nm in diameter, intermediate between the atomic and the bulk levels of matter. Nanotechnology has the promise to provide new materials such as biosensors that monitor and even repair bodily processes, microscopic computers, artificial bone, and lightweight, remarkably strong materials. To conceive and develop such materials, scientists need a thorough knowledge of the elements and their compounds. 

Sahin, O., Magonov, S., Su, C., Quate, C., and Solgard, O., An atomic force microscope tip designed to measure time-varying nanomechanical forces. Nature Nanotechnology, 336, 1037, 2007. 

The building blocks of all materials in any phase are atoms and molecules. Their arrangements and how they interact with one another define many properties of the material. The nanotechnology MBBs, because of their sizes of a few nanometers, impart to the nanostructures created from them new and possibly preferred properties and characteristics heretofore unavailable in conventional materials and devices. These nanosize building blocks are intermediate in size, lying between atoms and microscopic and macroscopic systems. These building blocks contain a hmited and countable number of atoms. They constitute the basis of our entry into new realms of bottom-up nanotechnology [97, 98]. 

Atomic force microscope (AFM) is a powerful nanotechnology tool for molecular imaging and manipulations. One major factor limiting resolution in AFM to observe individual biomolecules such as DNA is the low sharpness of the AFM tip that scans the sample. Nanoscale 1,3,5,7-tetrasubstituted adamantane is found to serve as the molecular tip for AFM and may also find application in chemically well-defined objects for calibration of commercial AFM tips [113]. 

However, the transition from nanoscience to nanotechnology had to come from yet a concnrrent innovation in tools used by scientists. This was the invention of the first scanning tunneling microscope (STM) in 1981 [60], followed by the invention of the atomic force microscope (ATM) in 1986 [61]. 

With electron microscopes providing the eyes, researchers explore the nanoworld. Miniaturization of electronics has reached the point where components of an integrated circuit can be as small as 0.000002 inches (50 nm), well within the scale of nanotechnology. Even more ambitious developments are on the drawing board or in the laboratory. As described below, some researchers are hoping to use atoms as building blocks to construct motors on a vanishingly small scale. 

Zettl s oscillator exerts control over the motion of a relatively small number of atoms, but the goal of some nanotechnology researchers is to manipulate atoms themselves. Thanks to the development of the Scanning Tunneling Microscope (STM) in 1981, this once unthinkable feat is not only possible, it has been performed. 

Hirsekorn, S., Rabe, U., and Arnold, W. (1997). Theoretical description of the transfer of vibrations from a sample to the cantilever of an atomic force microscope. Nanotechnology 8, 57-66. [295,298, 302]... 

Alternatives to photolithography are needed if we are to achieve smaller circuits and,hence, more powerful computers. The obvious solution is nanotechnology,through which circuits may be built atom by atom. One of the pioneering tools that will allow this to happen is the scanning probe microscope. As discussed in Chapter 5, scanning probe microscopes are not only able to produce images of individual atoms, they allow the operator to move individual atoms into desired positions. 

Nanotechnology concerns itself with the very small, but in so far as it is now a technology it mostly sells macroscopic quantities of microscopically controlled structures, and must make these by macroscopic techniques. Some proclaimed preparations... 

Progress in nanotechnology also depends critically on new developments in microscopy [42-45]. Compared to other investigation methods that help to explore the relation between the molecular structure and macroscopic properties, microscopy gives the most direct information. Particularly, in the case of disordered or aperiodic structures, visualisation of the structure is often more useful than indirect measurement and interpretation of its scattering properties. In practice, the utilisation and value of microscopes depends on their spatial resolution, the contrast and the imaging conditions. 

Figure 15.13 Schematic diagram of an atomic force microscope (image courtesy of the Opensource Handbook of Nanoscience and Nanotechnology).

Nanotechnology The science of designing, building or utilizing unique structures that are smaller than 100 nanometers (a nanometer is one billionth of a meter). This involves microscopic structures that are no larger than the width of some cell membranes. 

The promise of hottom-up nanotechnology has always depended on solving the problem of having a way to move individual atoms and molecules into desired positions. The best method yet developed to solve this problem is the family of scanning probe microscopes, which are now being used to produce a host of nanosize devices, some of which are discussed in the next section. DNA molecules may also become a powerful tool in the manipulation of atoms and molecules, although their potential has yet to be fully developed. 

Finally, one may use charging or polarization of surfaces, induced by external electric fields, to control the adsorption and desorption of molecules and the state of these adsorbed molecules, in order to control their chemical reactivity. This is an upcoming field that has not yet been explored to its fullest potential. It involves aspects of nanotechnology and nanoscience, like the fabrication of structures of several nanometers and stimuli generated by scanning tunneling microscopic probes. The outcome of the research in this field is generally of a fundamental nature. The topic of electronic control of reactions at surfaces will be discussed in the last section of this chapter. 

From a practical point of view, nanotechnology and nanosciences started in the early 1980s. Major developments were the birth of cluster science, the development of the scanning tunneling microscope, the discovery of buck-minsterfullerene (the C60 buckyball) and carbon nanotubes, as well as the synthesis of semiconductor nanocrystals, which led to the development of quantum dots [4]. 

Nanotechnology has brought new levels of sensitivity to detection technology. A prime example is the atomic force microscope (AFM), which detects small variations in the... 

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