Noticias26.07.2018Publicación del artículo “Quasi-parallel precession diffraction: Alignment method for scanning transmission electron microscopes.” |
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El Dr. Joaquim Portillo, responsable de la tecnología de MET Aplicada Materiales de los CCiTUB, ha publicado el artículo: “Quasi-parallel precession diffraction: Alignment method for scanning transmission electron microscopes” en la revista Ultramicroscopy. El artículo se ha llevado a cabo en colaboración con los investigadores siguientes: la Dra. Francesca Peiró, la Dra. Sònia Estradé y el Sr. Sergi Plana del departamento de Ingenierías de la Universitat de Barcelona, la Dra. Ute Kolb de la Johannes Gutenberg-Universität Mainz y el Dr. S.Nicolopoulos de la empresa NanoMEGAS SPRL. El artículo es producto una vez más de la colaboración Universidad-Empresa y, en este caso en concreto, en el marco del convenio existente entre la empresa NanoMEGAS SPRL y los CCiTUB. El resumen del artículo es el siguiente: "A general method to set illuminating conditions for selectable beam convergence and probe size is presented in this work for Transmission Electron Microscopes (TEM) fitted with µs/pixel fast beam scanning control, (S)TEM, and an annular dark field detector. The case of interest of beam convergence and probe size, which enables diffraction pattern indexation, is then used as a starting point in this work to add 100Hz precession to the beam while imaging the specimen at a fast rate and keeping the projector system in diffraction mode. The described systematic alignment method for the adjustment of beam precession on the specimen plane while scanning at fast rates is mainly based on the sharpness of the precessed STEM image. The complete alignment method for parallel condition and precession, Quasi-Parallel PED-STEM, is presented in block diagram scheme, as it has been tested on a variety of instruments. The immediate application of this methodology is that it renders the TEM column ready for the acquisition of Precessed Electron Diffraction Tomographies (EDT) as well as for the acquisition of slow Precessed Scanning Nanometer Electron Diffraction (SNED). Examples of the quality of the Precessed Electron Diffraction (PED) patterns and PED-STEM alignment images are presented with corresponding probe sizes and convergence angles". Para más información, pueden acceder al siguiente link: [+]. |
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