Influence of experimental conditions on atom column visibility in energy dispersive X-ray spectroscopy

• Published in: Ultramicroscopy Vol. 171; pp. 1 - 7
• Main Authors: Dycus, J.H., Xu, W., Sang, X., D'Alfonso, A.J., Chen, Z., Weyland, M., Allen, L.J., Findlay, S.D., LeBeau, J.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-12-2016
• Subjects: Atomic resolution; Collection; Convergence; Dwell time; Electron channeling; Energy dispersive x-ray spectroscopy; Forming; Optimization; Parameters; Probe convergence angle; Scanning transmission electron microscopy (STEM); X-rays; Probe convergence angle; Energy-dispersive X-ray spectroscopy; Scanning transmission electron microscopy (STEM); Atomic resolution; Electron channeling
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2016.08.013

Here we report the influence of key experimental parameters on atomically resolved energy dispersive X-ray spectroscopy (EDX). In particular, we examine the role of the probe forming convergence semi-angle, sample thickness, lattice spacing, and dwell/collection time. We show that an optimum specimen-dependent probe forming convergence angle exists to maximize the signal-to-noise ratio of the atomically resolved signal in EDX mapping. Furthermore, we highlight that it can be important to select an appropriate dwell time to efficiently process the X-ray signal. These practical considerations provide insight for experimental parameters in atomic resolution energy dispersive X-ray analysis.
•Impacts of microscope operating conditions on EDX signal and atom column contrast are demonstrated.•Influence of sample thickness and lattice spacing is shown.•Conditions for obtaining optimal signal and contrast for different sample types are discussed.•Effects of dwell time during EDX acquisition are discussed.