Optimizing thin film X‐ray spectra for quantitative analysis

Abstract

SUMMARY Energy dispersive X‐ray detectors are frequently attached to electron microscopes to enable microanalysis to be performed, but because such detectors accept X‐rays generated within an appreciable solid angle, the recorded spectra usually include some spurious contributions from the instrument. This paper describes instrumental modifications firstly to reduce and secondly to permit the subtraction of the residual extraneous contributions. The probable accuracy of this subtraction procedure is examined. Results are presented showing the effects of various instrumental modifications on spectra from thin specimens and demonstrate that by careful attention to experimental details it is possible to separate the spectrum due to the thin specimen alone from all other extraneous signals. Two test specimens and a number of test procedures for investigating the analytical performance of (scanning) transmission electron microscopes are presented. Sources of error and the method of their correction when the thin specimen Bremsstrahlung is used for quantitative analysis are discussed.