TABLE OF CONTENTS X-rays emitted from atoms represent the characteristics of the elements, and their intensity distribution represents the thickness-projected atom densities in the specimen. This is the energy dispersive X-ray spectroscopy (EDS), which has played an important role in microanalysis, particularly for heavier elements (Goldstein, et al., 1992). EDS is a key tool for identifying the chemical composition of a specimen. A modern TEM is capable of producing a fine electron probe of smaller than 2 nm, allowing direct identifi cation of the local composition of an individual nanocrystal. Shown in Fig. 2.54 is an EDS spectra acquired from a sample of nanocrystalline Ga-Sr-S. The peak intensity is directly related to the chemical composition of the corresponding element. Quantitative analysis gives Sr : Ga : S = 14 : 26 : 60, e.g., SrGa 2S 4. Detailed procedures can be found in Goldstein et al. (1992).
