{'fraction_non_alphanumeric': 0.02722177742193755, 'fraction_numerical': 0.0040032025620496394, 'mean_word_length': 5.476683937823834, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Non-Diffractive Electron Bessel Beams for Scanning Electron Microscopy in Transmission Mode Using Direct Phase Masks

Electron-beam shaping has drawn significant attention since the generation of an electron vortex beam has been successfully demonstrated [1,2]. Utilizing structured thin films or apertures which influence the amplitude and/or phase of an illuminating electron wave allows the production of specific types of electron beams. In this research project we focus on fabrication and application of non-diffractive electron beams [3,4] using direct phase masks (PMs) to create single beams with high intensity. Non-diffractive electron beams have a constant beam profile upon propagation possibly allowing focused imaging of thick samples in scanning modes in electron microscopy (EM) [5]. Additionally, non-diffractive beams theoretically have the smallest beam diameter and could thus even improve the resolution in EM. To our knowledge, electron-beam shaping has up to now only been applied in transmission (T)EM although it can be beneficial in scanning (S)EM, especially in combination with channelling effects. We present our recent progress in the fabrication of direct PMs for non-diffractive electron beams and their application.