Figure 23.3 — Carbon-based materials Figure 23.3 — Carbon-based materials. (a) Graphene is a two-dimensional building material for carbon materials of all other dimensionalities: it can be wrapped up into (zero-dimensional) buckyballs, rolled into (one-dimensional) nanotubes or stacked into (three-dimensional) graphite. (b, c) Carbon nanotubes were the first example of carbon nanostructures to be optically trapped.Figure (a) is reprinted by permission from Macmillan Publishers Ltd: Geim and Novoselov, Nature Materi. 6, 183–91, copyright 2007.Figures (b) and (c) are reprinted with permission from Maragò et al., Nano Lett. 8, 3211–16. Copyright (2008) American Chemical Society.