Effective medium theory for REELS analysis of amorphous carbon films

We use effective medium theory (EMT) as a framework to describe reflection electron energy loss spectra (REELS) from polycrystalline graphite and amorphous carbon (a‐C), the latter obtained by ion irradiation of the former. Such materials, isotropic at a macroscopic scale, are anisotropic at the micro‐ or nano‐scale. For them, we prove the value of the concept of effective isotropic energy loss function to describe EELS in the plasmon region. Based on this function, we calculate a differential inverse inelastic mean free path (DIIMFP) which, compared to experimental spectra from pristine and ion‐irradiated polycrystalline graphite, is able to reproduce their main features. Copyright © 2010 John Wiley & Sons, Ltd.