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Graphene examined with very slow electrons
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SYSNO ASEP 0450825 Druh ASEP C - Konferenční příspěvek (mezinárodní konf.) Zařazení RIV D - Článek ve sborníku Název Graphene examined with very slow electrons Tvůrce(i) Frank, Luděk (UPT-D) RID, SAI, ORCID
Mikmeková, Eliška (UPT-D) RIDCelkový počet autorů 2 Zdroj.dok. 12th Multinational Congress on Microscopy. - Budapest : Akadémiai Kiadó, 2015 - ISBN 978-963-05-9653-4 Rozsah stran s. 182-183 Poč.str. 2 s. Forma vydání Online - E Akce MCM 2015. Multinational Congress on Microscopy /12./ Datum konání 23.08.2015-28.08.2015 Místo konání Eger Země HU - Maďarsko Typ akce WRD Jazyk dok. eng - angličtina Země vyd. HU - Maďarsko Klíč. slova graphene ; 2D crystals ; ultra-low-energy STEM ; ultra-low-energy SEM Vědní obor RIV JA - Elektronika a optoelektronika, elektrotechnika CEP TE01020118 GA TA ČR - Technologická agentura ČR Institucionální podpora UPT-D - RVO:68081731 Anotace Electron microscopy of materials composed of light elements suffers from low image contrast, particularly in the transmission microscopy of biomedical specimens. Post-fixation or staining with heavy metal salts that highlight certain structural details is a partially successful aid in routine microscopy. In order to examine mutually overlapped flakes of two-dimensional crystals such as graphene we need to obtain a contrast contribution from a single layer of carbon atoms. This task requires increasing the scattering rate of incident electrons by means of a drastic lowering of their energy to hundreds of eV or less. The cathode lens principle implemented in the SEM, and recently in the STEM mode as well, makes it possible to use an arbitrarily low energy in both reflection and transmission modes. Contrasts between sites differing in thickness by a single graphene layer are demonstrated at 220 eV. The high lateral resolution of ultra-low-energy STEM with a cathode lens enabled us to measure graphene transmissivity accurately down to 1 eV for 1 to 7 graphene layers. Surprisingly, below 50 eV the transmissivity does not increase as one would expect from the usual behaviour of the inelastic mean free path of electrons, but remains within a range of units of percent. Pracoviště Ústav přístrojové techniky Kontakt Martina Šillerová, sillerova@ISIBrno.Cz, Tel.: 541 514 178 Rok sběru 2016
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