Role of electronic band structure and resonances on electron reflectivity and vibrational excitation functions: The case of hydrogenated diamond

We report on an high resolution electron energy loss study of electron surface reflectivity and excitation of the C–H stretch mode of hydrogenated polycrystalline diamond films at low energy. Their specular energy dependences demonstrate that (i) the reflectivity is dominated by the conduction band structure. In particular the second absolute band gap of bulk diamond results in a strong increase of the elastic backscattered intensity around 13.5 eV. (ii) The vibrational excitation is dominated by a negative ion resonance process around 8 eV and a band gap induced scattering enhancement around 13 eV.