Existing absorption correction programmes used in quantitative electron probe microanalysis are assessed and their limitations discussed. It is shown that the Philibert absorption correction models (Philibert 1963) may be significantly improved by the adoption of new expressions for the a and h terms. A new absorption correction proposed by Bishop (1974) is also investigated and its range of applicability is found to be greater than either of the two Philibert models. Accuracy of the Bishop approach has been improved by introducing a new expression for the mean depth of X-ray emission which is derived from a detailed study of electron-solid interactions using a Monte Carlo simulation of electron trajectories. Data from the Monte Carlo programme are also used in the development of a new atomic number correction. This new correction procedure overcomes some of the limitations in the Duncumb and Reed approach (Duncumb and Reed 1968) and provides an important advance in the field since it permits the computation of correction factors for specimens inclined to the incident electron beam. Applications of quantitative electron probe microanalysis to research in both materials science and biology are described, the new data providing information which has advanced our understanding in diverse fields of study such as growth processes of avian eggshells and oxidation mechanisms in polymeric materials. Complementary research using other electron optical techniques such as scanning and transmission microscopy is also described. These instruments have been employed to study the microstructure of materials and, more particularly, to provide quantitative data on defect populations in thin foils. In addition new techniques of foil thickness measurement are assessed and the prospects for improvement in this area are discussed.
|Date of Award||1978|