Raman spectra of iron-modified amorphous carbon

Raman spectra of amorphous carbon films containing encapsulated iron (a-C:Fe) have been measured in the frequency range 200–1000 cm−1. The concentration of encapsulated iron atoms (3, 26, 38, and 54 at. %) was controlled by changing the relative areas of iron and graphite targets during the film deposition by RF magnetron sputtering and checked by Rutherford backscattering. The Raman spectra of a-C:Fe films display a series of almost equidistant bands spaced by approximately 110 cm−1. This character of the spectrum is explained in terms of the atomic vibrations in short carbon nanotubes formed during the introduction of iron into an amorphous carbon matrix.