Atomic arrangement of iodine atoms inside single-walled carbon nanotubes

We report atomic resolution Z-contrast scanning transmission electron micro scopy images that reveal the incorporation of I atoms in the form of helica l chains inside single-walled carbon nanotubes. Density functional calculat ions and topological considerations provide a consistent interpretation of the experimental data. Charge transfer between the nanotube walls and the I chains is associated with the intercalation.