Nanoscale Materials

Few terms in the chemical and physical sciences have seen more use (and abuse) in recent years than “nanoscience” or, even worse, “nanotechnology”. Why all the interest and hype? Explaining the interest in this subject is relatively easy. The past 15 years or so have witnessed an explosion of relatively inexpensive analytical tools, such as scanning probe microscopies, for interrogating and manipulating materials on the nanometer length scale. At the same time, several previously unrelated fields have begun to focus on understanding and controlling physical and chemical phenomena on nanometer length scales. In electrical engineering, complimentary metal oxide semiconductor (CMOS) based transistors have been fabricated with gate widths of 50 nm. The same lithographic techniques that defined the features of that transistor have been utilized to attach two electrodes to a single molecule. In biology, experiments that probe the dynamics of single cells, single proteins, and single DNA strands have been carried out, and the operational mechanisms of certain biomolecular motors and gears have been elucidated. At the same time that scientists and engineers are planning to build terabit (1012 cm-2) memories, the sequencing of the human genome is nearing completion. In addition, nanoscale materials have truly come of age. Physical scientists have learned how to manipulate crystallization processes such that nanometer- or even angstrom-level control over size and shape is now possible for a wide variety of materials. Nanocrystals that are of the quality of high-grade electronic materials are now prepared by routine synthetic procedures, and single-walled carbon nanotubes have been demonstrated to be stronger fibers with better electronic properties than anything previously known.