Secondary-electron emission and electron-energy-loss results on graphite single crystals

Abstract
Unoccupied states of graphite single crystals have been probed in a wide energy range. Angle-resolved secondary-electron emission excited by electrons has been used to map out the unoccupied bands above the vacuum level. Highly dispersive structures are observed in the 030-eV kinetic-energy range of the electron yield collected along the Γ–M and Γ–K symmetry directions of the two-dimensional Brillouin zone. The results are in good agreement with recent band-structure calculations. The angular dependence of plasmons has been investigated and clear effects related to graphite anisotropy are observed and interpreted.