ABSTRACT
I. INTRODUCTION The preparation and characterization of size-quantized nanoparticles are receiving ever increasing attention by material scientists, physicists, chemists, and biologists. Mechanical manipulation is the predominant strategy physicists have employed in their preparations of nanoparticles and nanostructured materials. At the low end of the scale, this involves the exhaustive grinding or milling of bulk materials [1]. Examples at the high technological end include single-atom transfer from one site to another, relocation of small molecular clusters from surfaces, and etching or deposition of materials in subnanometer regions [2]. Generation of atomic and molecular clusters via gas condensation in an ultrahigh vacuum [3] falls between these two extremes. In general, any nanoparticle can be fabricated by physical methods and band gap engineering permits the construction of semiconductor superlattices with any desired nanoscale architecture. The high cost involved in these methods does not, however, conveniently lend itself to the large-scale production of advanced nanoparticles and nanostructured materials.
