Schematic structure of an idealised, simplified, and unfolded, shell-like a-C nanoparticle, C₄₃H₄₀, which could also be a substructure within a larger a-C(:H) nanoparticle network. The dashed green arrows indicate the common linking bonds that close the shell structure. The red dots indicate the equally probable (i.e. lowest energy) bond cleavage sites. The unadorned, dangling bonds mark the positions of H atoms.