The Nature and Characterization of Nanoparticles
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1184-HH04-01
The Nature and Characterization of Nanoparticles
Rajiv Kohli The Aerospace Corporation, Houston, TX 77058-1521, U.S.A.
ABSTRACT Nanosize particles are of fundamental and practical interest for developing advanced materials and devices and micro and nanostructures. As feature sizes shrink, nanoparticle contamination is also becoming increasingly important to achieve and maintain high product yields. In order to employ appropriate material and product development strategies, or institute preventive assembly and remediation strategies to control nanoparticle contamination, it is essential to understand the nature of nanoparticles and to characterize these particles. Particles in the size range 0.1 nm to 100 nm present unique challenges and opportunities for their imaging and characterization. Critical information for this purpose is the number and size of the particles, their morphology, and their physical and chemical structure. Because of this importance, many advances and new developments have been made in qualitative and quantitative characterization techniques for particles in this size range, including neutron holography, three dimensional atom probe imaging, ultrafast microscopy and crystallography, magnetic resonance force microscopy, and high-resolution x-ray crystallography of non-crystalline structures. It is now possible to completely characterize nanoparticles from 0.1 nm to 100 nm size. A brief review of the nature of nanoparticles is presented and recent developments in selected characterization techniques are described.
INTRODUCTION In high technology applications across many industrial sectors, component and feature sizes are continually shrinking. The development of new materials for many of these applications involves particle interactions at the nanometer or smaller scale. At the same time, there is increasing realization that further advances in the medical field will require understanding of cellular phenomena at atomic and molecular levels. Characterization of nanometer size particles is essential to understanding their fundamental interactions and their behavior. As an illustration of the importance of characterization at this scale, a new Advanced Materials Laboratory for materials characterization at the near-atomic level has been established at the National Institute of Standards and Technology (NIST) in the United States with stringent environmental controls [1]. This laboratory sets the standard for developing, testing and demonstrating instruments for atomic-level characterization of materials. More recently, a workshop devoted exclusively to the nanostructure problem was held at NIST [2]. The aims of the workshop were to elucidate the challenges associated with accurately determining atomic positions at the nanoscale. This is still a formidable challenge because atom positions must be known to very high precision of the order
of 0.01 Å to 0.001 Å (1 Å = 10-10 m) needed for theoretical calculations of electronic structure and the functional properties of nanostructured m
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