Toward Single Mode, Atomic Size Electron Vortex Beams
2014 (English)In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 20, no 3, 832-836 p.Article in journal (Refereed) Published
We propose a practical method of producing a single mode electron vortex beam suitable for use in a scanning transmission electron microscope (STEM). The method involves using a holographic "fork" aperture to produce a row of beams of different orbital angular momenta, as is now well established, magnifying the row so that neighboring beams are separated by about 1 mu m, selecting the desired beam with a narrow slit, and demagnifying the selected beam down to 1-2 angstrom in size. We show that the method can be implemented by adding two condenser lenses plus a selection slit to a straight-column cold-field emission STEM. It can also be carried out in an existing instrument, the monochromated Nion high-energy-resolution monochromated electron energy-loss spectroscopy-STEM, by using its monochromator in a novel way. We estimate that atom-sized vortex beams with <= 20 pA of current should be attainable at 100-200 keV in either instrument.
Place, publisher, year, edition, pages
2014. Vol. 20, no 3, 832-836 p.
vortex beam, STEM, fork aperture, monochromator
IdentifiersURN: urn:nbn:se:uu:diva-230527DOI: 10.1017/S143192761400083XISI: 000339158700024OAI: oai:DiVA.org:uu-230527DiVA: diva2:741652