Scanning probe microscopes nanotechnology

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. 

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. 

Nanotechnology. Nanotechnology is an example of a scientific discipline whose very existence simply would not be possible without the use of extremely powerful microscopes. This emerging field takes advantage of the special ways in which molecules behave at the nanoscale to create nanoscale machinery such as tiny sensors that can detect and tally the number of specific types of molecules in a sample of chemicals or nanoparticles that systematically seek out and destroy cancerous cells within a patient s body. Op>-tical microscopes do not have the magnifying power necessary to clearly resolve objects at the nanoscale (about 1-100 nanometers, or about one-thousandth the width of a strand of human hair), so electron microscopes and scanning probe microscopes serve as the foundational tools of nanoscientists. 

The growing needs of nanotechnology are inspiring further developments in microscopy. A scanning probe microscope built for the Argonne National Laboratory in Illinois allows researchers to see into an individual atom and observe its ms -netic spin. The microscope, which cost 2 million, is itself very small—but it must be placed inside a machine 16 feet high and located in a soundproof room, so as to prevent even the tiniest vibration to throw off its focus. 

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. 

The development of surfaces with making use of probes of scanning tunneling microscopes (STM) and atomic-force microscopes (AFM) seems to be the first nanotechnology approach in exploration of unique properties of nanostructures in nanoeleetronics and nanosystems [1],... 

Computer picture of the Rice University nanocar and its roll guided hy the probe of a scanning tunneling microscope (STM) (The Richard Smalley Institute for Nanotechnology, Rice University)... 

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