2/10/2024 0 Comments Beam raster scan![]() However, in most cases, such damage to the sample is usually considered to be detrimental. This effect can be very useful, for example, allowing electron energy loss spectroscopy (EELS), or for the deliberate sculpting of nano-device components, or to excite diffusion of single atoms and vacancies. Beam damage occurs when the electron beam used to form the image transfers a critical amount of energy to the sample being examined, potentially causing damage or otherwise changing the subject of the experiment. ![]() The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.īeam damage, drift distortion, and scan distortion are inherent issues that hinder quantitative interpretation of scanning transmission electron microscopy (STEM) imaging. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. A method to allow extremely fast scanning with a uniform residence time would enable imaging at low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution.
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