Journal of Electron Microscopy Advance Access originally published online on February 15, 2007
Journal of Electron Microscopy 2006 55(6):281-288; doi:10.1093/jmicro/dfl038
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Observation of the anisotropy of the inelastic scattering of fast electrons accompanied by the K-shell ionization of a carbon nanotube
EcoTopia Science Institute, Nagoya University Furo-cho Chikusa-ku, Nagoya 464-8603, Japan
*To whom correspondence should be addressed. E-mail: saitoh{at}esi.nagoya-u.ac.jp
The angular distribution of inelastically scattered electrons following the carbon K-shell ionization of a carbon nanotube (CNT) has been studied by using an energy-filtered transmission electron microscope. The energy-filtered scattering patterns of the CNT, whose cylindrical axis is oriented in the perpendicular direction with respect to the incident-electron beam, show anisotropic angular distributions caused by the p symmetry in the 
* and 
* unoccupied states into which a K electron jumps, and the cylindrical shape of the CNT. Corresponding inelastic scattering cross sections, differential in solid angle, have been calculated within the first Born approximation by considering that each carbon atom has three, mutually orthogonal, unoccupied p orbitals, which are oriented in directions perpendicular or parallel to the tube surface. The observed angular patterns agree well with theoretical results, which are linear combinations of the differential cross sections accompanied by the transitions to * and * states. A series of the fittings of the experimental patterns at successive values of energy loss provides magnitudes of the * and * components, which can be called partial electron energy-loss spectra accompanied by the transitions to the * and * states.
Keywords inelastic scattering, inner-shell excitation, EFTEM, EELS, anisotropy, carbon nanotube
Received 17 October 2006, accepted 12 December 2006