In situ observation of the formation and stability of single fullerene molecules under electron irradiation

Single fullerene cages are generated by irradiating different carbon specimens with electrons in an electron microscope. The process is non-thermal and slow and hence accessible to direct observation. Under irradiation, lattice planes unwind from graphitic particles, bend and close by forming irregular cages which shrink and undulate until fullerene-like spherical cages are left. These prove to be stable under intense irradiation in contrast to C60 molecules within fullerite crystals. A mechanism based on sputtering and exchange of atoms by collisions with electrons from the beam is proposed to explain the formation and stability of fullerene molecules on graphitic surfaces.