STEM exposes isotopes in graphene
Austria-based researchers have used STEM to measure isotopes within nanometre-sized regions of graphene.
According to Professor Jani Kotakoski from the University of Vienna, the same energetic electrons that would form an image of the graphene, also eject one atom at a time due to scattering at a carbon nucleus.
By analysing the number of electrons that, on average, are required to eject an atom, researchers can estimate the local isotope concentration.
Kotakoski and colleagues used a Nion UltraSTEM100 for isotope analysis but as Kotakoski highlights: "Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials."
Using STEM to determine isotope concentrations in 2D materials.
Research is published in open access journal, Nature Communications, with microscopy data uploaded onto the open repository, Figshare.
"To our knowledge, this is the first time electron microscopy data have been openly shared at this scale," points out Kotakoski's colleague, Toma Susi.
The researchers have a patent pending on their method and as Kotakoski concludes: " "Modern microscopes already allow us to resolve all atomic distances in solids and to see which chemical elements compose them. Now we can add isotopes to the list."
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