EELS study of the irradiation-induced compression of carbon onions and their transformation to diamond Original Research Article

The irradiation-induced self-compression of carbon onions and their transformation to diamond crystals are studied in situ by electron energy loss spectroscopy at high specimen temperature in a high-voltage electron microscope. Plasmon peaks in the low-loss region and the carbon K edge with the near-edge fine structure exhibit characteristic changes during irradiation. The spectra show the increasing electron density and the gradual change from sp2 to sp3 character of bonding during the selfcompression of carbon onions. The spectra of the diamond cores correspond closely to those of cubic high-pressure diamonds.