Microbeam technique for energy‐dispersive x‐ray fluorescence

By using the total reflecting properties of x-rays inside glass capillary tubes, intense fine or microbeams of x-rays can be obtained. In combination with conventional diffraction x-ray tubes, microbeams with a diameter of a few micrometres and with an intensity sufficient for trace element analysis can be achieved. The basic physics behind the capillary technique is reviewed and an energy-dispersive x-ray fluorescence microbeam spectrometer for trace element analysis is described. Examples of applications of the microbeam spectrometer are given and the future perspectives of the capillary technique are discussed.