Electron-beam analysis of polymerized KC60

We have conducted high-resolution transmission electron microscopy (HRTEM) and electron-energy-loss spectroscopy (EELS) studies on polymerized KC60. The chainlike structure proposed for the polymerized material is confirmed. Lattice constants extracted from the HRTEM images are consistent with those determined earlier by x-ray diffraction. The fine structure in the EELS spectrum of KC60 shows the sp(2) nature of the carbon bonds along with features which distinguish the bonding in this alkali fulleride from that of other fullerenes. Both the HRTEM and EELS studies show that polymerized KC60 is exceedingly resilient against damage induced by a 200-keV electron beam, in sharp contrast to the behavior of pristine C-60.