Conventionally, x-ray microanalysis on scanning electron microscopes (SEM) with energy dispersive spectrometers (EDS) has been performed with relatively high primary energies (>10 kv). for most samples this results in reasonably good separation of the generated x-ray line series from different elements enabling unambiguous identification and therefore accurate qualitative analysis. Under these circumstances it is widely accepted that quantitative analysis of polished bulk samples is possible on a routine basis with relative errors around 1-5% and detection limits of the order of 0.1%.

However, in order to address the analysis requirements of new advanced materials with sub-micron features, there is growing interest in performing x-ray microanalysis at low beam energies(<5kv). this is now a more realistic goal due to the routine availability of field emission sem's which can operate with much improved beam sizes at low beam energies with sufficient beam current to perform practical microanalysis, in conjunction with the improved low energy performance of current, commercially available EDS systems.