Optical constants of hydrogenated amorphous carbon in the range 0–100 eV

The dielectric behavior of hydrogenated amorphous carbon samples, prepared by keV-Ar-ion bombardment of a polystyrene matrix, in the energy range 0–100 eV has been studied in connection with the change in hydrogen content. The wide-ranging results obtained by means of electron-energy-loss spectroscopy in reflection mode have been successfully compared with the optical constants available in the 1–6 eV range, resulting from the combined use of transmittance and reflectance experimental spectra. A strong rearrangement of the σ→${\mathrm{\sigma }}^{\mathrm{*}}$ transitions is evidenced in the bulk loss function Im(-1/ɛ̃) together with a change in the relative oscillator strengths, on going from pure amorphous carbon to the most hydrogenated (${\mathit{x}}_{\mathit{H}}$=40%) α-C:H sample.