Scanning Electron Microscopy (SEM)

Abstract

Today, scanning electron microscopy (SEM) is a versatile technique used in many industrial labs, as well as for research and development. Due to its high lateral resolution, its great depth of focus and its facility for X-ray microanalysis, SEM is often used in materials science – including polymer science – to elucidate the microscopic structure or to differentiate several phases from each other. After a brief historic overview, this chapter explains the assembly and the mode of operation of SEM, which deviates from standard microscopes. This includes descriptions of the fundamentals of electron optics, the electron optical column, and the physical basics of electron–specimen interactions, which aid the understanding of contrast formation and charging effects. Because it is important to know the factors that influence X-ray microanalysis, a separate section about the origins of X-ray spectra and their interpretation has also been added. A discussion of environmental scanning electron microscopy (ESEM™) – a special development of SEM that is particularly useful when nonconducting or “wet” samples are to be examined – completes the chapter.