A numerical model for multiple detector energy dispersive X-ray spectroscopy in the transmission electron microscope

• Published in: Ultramicroscopy Vol. 164; pp. 51 - 61
• Main Authors: Xu, W., Dycus, J.H., Sang, X., LeBeau, J.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-05-2016
• Subjects: Absorption; Counting; Detector collection angle; Detectors; Electron microscopes; Energy dispersive X-ray spectroscopy (EDS); Filtering; Mathematical analysis; Mathematical models; Quadrants; Shadowing; Spurious X-rays; Super-X; X-ray absorption correction; Super-X; Energy dispersive X-ray spectroscopy (EDS); X-ray absorption correction; Detector collection angle; Shadowing; Spurious X-rays
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2016.02.004

Here we report a numerical approach to model a four quadrant energy dispersive X-ray spectrometer in the transmission electron microscope. The model includes detector geometries, specimen position and absorption, shadowing by the holder, and filtering by the Be carrier. We show that this comprehensive model accurately predicts absolute counts and intensity ratios as a function of specimen tilt and position. We directly compare the model to experimental results acquired with a FEI Super-X EDS four quadrant detector. The contribution from each detector to the sum is investigated. The program and source code can be downloaded from https://github.com/subangstrom/superAngle.
•A novel numeric model is developed to predict the effective detector collection angle for multi-detector EDS in the transmission electron microscope.•The precise geometry of specimen holder is incorporated to determine the influence of holder shadowing•The role of X-ray filtering by the Be specimen carrier is investigated.•Predicted counts and intensity ratios are directly compared to experiment as a function of tilt and are shown to be in excellent agreement•The detector intensity sum effectively reduces errors compared to the individual detector signals.