Characteristic Energy Losses of Electrons in Carbon

The values reported for the characteristic energy losses of electrons in carbon vary by as much as 50%. In an attempt to resolve this discrepancy the electron energy losses have been remeasured for evaporated carbon and natural graphite, and it is found that there is a large difference for these two forms of carbon. Electron diffraction patterns of evaporated carbon show it to be highly amorphous. Annealing of the films causes growth of the crystallites, and also an increase of the energy loss toward the loss values for graphite. It is shown by calculation that the difference in the energy losses for the two forms is due to a difference in density, and that annealing increases the density of the evaporated carbon and, therefore, the energy loss value.