Abstract
Solid state forms of pure C 60 and C 70 were investigated at room temperature using transmission electron microscopy (TEM) techniques incorporating electron diffraction, high resolution TEM (HRTEM) and electron energy loss spectrometry (EELS). Electron diffraction patterns recorded along several zone axes indicated that C 60 has a face centered cubic unit cell with Fm3m space group symmetry and lattice parameter of 1.42 nm within 5% experimental error. C 70 appears to adopt close packed hexagonal symmetry (P6 3/mmc space group) with a 0 = 1.01 nm and n 0 = 1.68 nm within 5% experimental error. HRTEM imaging revealed the presence of extensive periodicity associated with C 60 and C 70 crystallites as well as numerous lattice defects and faults. EELS low loss spectra for C 60 and C 70 solids exhibit excitations analogous to graphite and amorphous carbon, such as interband π and π + σ plasmons, though at slightly lower energy losses. C 70 exhibits a more intense “π plasmon” than C 60. The 1s core loss spectra of both C 60 and C 70 show a π* transition at 285 ± 0.5 eV, and splitting of a σ* transition centered at 291 ± 0.5 eV.
Published Version
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