Graphene, a sheet of carbon one atom thick, has properties that are distinct from other forms of carbon—even graphite, which is just a bulk collection of graphene sheets. That's prompted researchers to look into other forms of what are called two-dimensional materials (at an atom thick, the third dimension isn't counted). And now, they've started experimenting with one-dimensional materials, which are essentially a line of single atoms.
Unfortunately, single atoms aren't especially cooperative about getting in line. Even stable crystals, like those formed by a salt, stay together in part because there are multiple interaction partners for each atom that stabilize the structure. Putting atoms in a line gets rid of most of these interactions, leaving the remaining ones unstable.
But researchers have figured out a way around this problem: they've managed to pack a line of atoms inside a carbon nanotube. Having chosen cesium iodide for their work, they simply had to pick a diameter that was larger than the atoms (over 3.4 Angstroms) but smaller than you'd need to put two atoms side-by-side (less than 8 Angstroms). They chose double-walled carbon nanotubes and loaded them with CsI simply by vaporizing the chemical under pressure.To read more, click here.