TABLE OF CONTENTS Nanomaterials are dominated by particles with sizes in nanometer range. Imaging atoms and quantitative analysis of surface chemistry are vitally important for nanomaterials research. Transmission electron microscopy (TEM) is a powerful and unique technique for structure characterization, which not only can provide real space imaging at a resolution of 1 2 (1 = 1 10 ?10 m), but also an analytical tool for quantitative structure and chemical analysis. By forming a nanometer size electron probe, TEM is unique in identifying and quantifying the chemical and electronic structures of individual nanocrystals. In situ TEM is demonstrated for characterizing and measuring the properties of individual nanostructures, such as the bending modulus of a carbon nanotube, from which the structure-property relationship can be registered with the structure of the nanoparticle. This is a unique application of TEM and it is a new direction in nanomeasurements (Wang, 1999). The objective of this chapter is to introduce the fundamentals of TEM and its applications in structural determination of nanomaterials.
A modern TEM is schematically shown in Fig. 2.1. It is composed of an illumination system, a specimen stage, an objective lens system, the magnification system, the data recording system (s), and the chemical analysis system. The electron gun typically uses an LaB6 thermionic emission source or a field emission source. The LaB6 gun gives a high illumination current, but the current density and the beam coherence are not...
