Transmission Electron Microscopy and its use for the study of paints and pigments

Abstract

This chapter emphasizes on the principles underlying the formation of transmission electron diffraction patterns, in particular the selected area diffraction (SAD) and the convergent beam electron diffraction (CBED) patterns. It then proceeds to give examples of studies taken from small paint fragments from two artworks in which the CBED technique was used in conjunction with energy dispersive x-ray analysis (EDAX) to determine the mineral composition of the fragments. The transmission electron microscope (TEM), with an EDS detector attached, is another very powerful instrument that has been used in materials science and crystallography for a long time, but it is used little in conservation. TEM was employed and even fewer cases where electron diffraction was used, authors usually reported using the technique only to obtain very high magnifications of images. There are many obvious advantages to TEM, mainly its ability to give simultaneous elemental composition using EDS and crystal structure information by selected area diffraction (SAD) or convergent beam electron diffraction (CBED). It might be noted that the spatial resolution of a TEM can be improved by an order of magnitude, and by the use of a parallel electron energy loss detector.