Kis A Csányi G Salvetat JP Lee TN Couteau E Kulik AJ Benoit W Brugger J Forró L 2004 During their production, single-walled carbon nanotubes form bundles. Owing to the weak van der Waals interaction that holds them together in the bundle, the tubes can easily slide on each other, resulting in a shear modulus comparable to that of graphite. This low shear modulus is also a major obstacle in the fabrication of macroscopic fibres composed of carbon nanotubes. Here, we have introduced stable links between neighbouring carbon nanotubes within bundles, using moderate electron-beam irradiation inside a transmission electron microscope. Concurrent measurements of the mechanical properties using an atomic force microscope show a 30-fold increase of the bending modulus, due to the formation of stable crosslinks that effectively eliminate sliding between the nanotubes. Crosslinks were modelled using first-principles calculations, showing that interstitial carbon atoms formed during irradiation in addition to carboxyl groups, can independently lead to bridge formation between neighbouring nanotubes. https://sonar.ch/global/documents/278964 eng info:eu-repo/semantics/altIdentifier/doi/10.1038/nmat1076 info:eu-repo/semantics/altIdentifier/pmid/14991016 Nature materials. - 2004 Beta Particles Cross-Linking Reagents Microscopy, Electron Nanotubes, Carbon Tensile Strength Reinforcement of single-walled carbon nanotube bundles by intertube bridging. http://purl.org/coar/resource_type/c_6501