ANALYTICAL AND LAB EQUIPMENT BEXvs EDS Dr Haithem Mansour and Dr Simon Burgess explore the differences between BEX imaging and EDS mapping C


onventional X-ray mapping, the basis of energy dispersive spectroscopy (EDS), has been around for many years. A


backscattered electron image is first generated by the scanning electron microscope (SEM), then an X-ray map is acquired. It requires a prescribed working distance and elevated beam; the map being built up gradually under conditions optimised to ensure accuracy and throughput from a conventional EDS detector. By contrast, backscattered electron


and X-ray (BEX) imaging employs the seamless and simultaneous integration


of these two signals into a single image to understand a sample much more quickly and in more detail, and in essence, generates real-time imaging at a wide range of working distances and imaging conditions. The most important signals, in this case, are electrons (for topography and materials contrast) and X-ray (for constituent elements). If you spend a lot of your SEM time


doing all the exploratory work before collecting any of the data you actually want to analyse or report, then you will find the BEX technique liberating. A SEM without BEX is like driving a car without GPS or watching some films in


black and white; you can, but its either not as quick nor easy as it should be, or it is missing some critical details to achieve a satisfactory outcome or experience.


A UNIQUE NEW DESIGN To achieve this, Unity, the world’s first BEX detector,


is a radically different


type of detector which collects significantly more X-rays and is comparatively unaffected by sample height compared with conventional side mounted EDS detectors, due to being located directly below the microscope pole piece.


22 www.scientistlive.com


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