Atomic-Resolution Imaging of Small Organic Molecules on Graphene

Here, we demonstrate atomic-resolution scanning transmission electronmicroscopy (STEM) imaging of light elements in small organic molecules on graphene.We use low-dose, room-temperature, aberration-corrected STEM to image 2Dmonolayer and bilayer molecular crystals, followed by advanced image processingmethods to create high-quality composite images from similar to 102-104individual molecules.In metalated porphyrin and phthalocyanine derivatives, these images contain anelementally sensitive contrast with up to 1.3 A resolution???sufficient to distinguishindividual carbon and nitrogen atoms. Importantly, our methods can be applied tomolecules with low masses (similar to 0.6 kDa) and nanocrystalline domains containing just a few hundred molecules, making it possible tostudy systems for which large crystals cannot easily be grown. Our approach is enabled by low-background graphene substrates,which we show increase the molecules'critical dose by 2-7x. These results indicate a new route for low-dose, atomic-resolutionelectron microscopy imaging to solve the structures of small organic molecules

Automated summary

Here, we demonstrate atomic-resolution scanning transmission electron microscopy (STEM) imaging of light elements in small organic molecules on graphene. Our approach involves low-dose, room-temperature, aberration-corrected STEM to create high-quality composite images, with sufficient resolution to distinguish individual carbon and nitrogen atoms.