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Transmission of very slow electrons as a diagnostic tool

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    0507132 - ÚPT 2020 RIV CZ eng C - Konferenční příspěvek (zahraniční konf.)
    Frank, Luděk - Nebesářová, Jana - Vancová, Marie - Paták, Aleš - Mikmeková, Eliška - Müllerová, Ilona
    Transmission of very slow electrons as a diagnostic tool.
    NANOCON 2013 - 5th International Conference Proceedings. Ostrava: TANGER Ltd, 2014, s. 503-508. ISBN 978-80-87294-47-5.
    [International Conference NANOCON 2013 /5./. Brno (CZ), 16.10.2013-18.10.2013]
    Grant CEP: GA ČR GAP108/11/2270; GA TA ČR(CZ) TE01020118
    Institucionální podpora: RVO:68081731 ; RVO:60077344
    Klíčová slova: electron microscopy * slow electrons * STEM * graphene * ultrathin tissue sections
    Obor OECD: Nano-materials (production and properties); Civil engineering (BC-A)

    The penetration of electrons through solids is retarded by sequences of their interactions with the matter in which the electron changes its direction of motion and loses its energy. Inelastic collisions, the intensity of which reaches a maximum at around 50 electronvolts (eV) and drops steeply on both sides of this fuzzy threshold, are decisive for the penetration of electrons. Transmission microscopy (TEM or STEM) observes thin samples of tens to hundreds of nanometres in thickness by passing electrons of energies of tens to hundreds of kiloelectronvolts through them. The range below 50 eV has recently been utilized in the examination of surfaces with reflected electrons, where high image resolution is achieved thanks to the retardation of electrons close to the sample surface in the ´cathode lens´ . In this lens, the role of the cathode is played by the sample itself, biased to a high negative potential. This principle can also be utilized in the transmission mode with samples of a thickness at and below 10 nm. This method has recently been implemented and verified on graphene samples prepared by various methods. The results have made it possible to diagnose the continuity and quality of the graphene flakes. Furthermore, series of experiments have been performed involving the observation of ultrathin tissue sections with electrons decelerated to about 500 eV and less, where they provide an image contrast of the cell ultrastructure much higher than that provided by traditional microscopic modes.
    Trvalý link: http://hdl.handle.net/11104/0298349

     
     
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