A new atomic number correction is proposed for quantitative electron-probe microanalysis. Analytical expressions for the stopping power S and back-scatter R factors are derived which take into account atomic number of the target, incident electron energy and overvoltage; the latter expression is established using Monte Carlo calculations. The correct procedures for evaluating S and R for multi-element specimens are described. The new method, which overcomes some limitations inherent in either the Duncumb and Reed (1968) or the Philibert and Tixier (1968) atomic number corrections, may readily be used where specimens are inclined to the electron beam.

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A new correction procedure for converting electron-probe microanalysis measurements into true weight concentration is proposed. It incorporates a new atomic number correction and an absorption correction based upon Bishop's model (1974). Unlike earlier treatments the model does not have to rely upon any empirical optimisation of input parameters. The correction procedure has been tested by applying it to a wide range of microanalysis data including light-element results, and it is shown to give greater accuracy than the established methods.

For pt.I see ibid., vol.18, p.1233 (1985). A new absorption correction is developed which is shown to work well for quantitative analysis of all systems including light elements. It is based upon representing the X-ray depth distributions as a quadrilateral shape defined by the mean depth of X-ray generation and the position and relative height of the peak in the X-ray depth profile. Equations for describing these parameters in terms of target material, incident electron energy, etc. are derived by reference to tracer and Monte Carlo determinations of X-ray depth distributions.

Contamination in electron optical equipment may occur in the form of carbonaceous deposit on the specimen undergoing analysis or condensation and/or polymerisation of extraneous matter upon other components of the instrument. Almost without exception these effects are undesirable and in this paper we review sources of contamination and discuss methods of minimising the problem.