Detection of ultra-soft X-rays with a variable geometry proportional counter fitted to a transmission electron microscope (TEM)

SUMMARY The ability of an end-window variable geometry flow proportional counter to detect the ultrasoft BeK and SiL X-ray lines induced by the electron beam of a transmission electron microscope (TEM) has been demonstrated. This counter has been used in the current work in the energy dispersive mode, and has been equipped with a Formvar window about 400 nm thick, aluminized on both sides with a layer of 65 nm total thickness. X-ray peaks generated by specimens of other light elements such as boron, carbon, oxygen, fluorine and aluminium, and detected with this technique, are also reported. In the case of the BK line, the counting rate obtained with this detector has been evaluated and compared with that of a crystal spectrometer equipped with a conventional side-window flow proportional counter. Finally, a linear relationship between X-ray energy and detected pulse height was found for the lines examined, i.e. from the SiL up to the SiK X-rays.