Electron-energy-loss spectroscopy has been used to identify microcrystalline diamond films produced by laser ablation of graphite. The production of the diamond phase results from varying the deposition geometry and parameters from those of an earlier configuration that produced diamondlike carbon films. A complete study of these crystalline and amorphous materials indicates a plasmon energy variation for films produced in different environments. Spectra taken with different primary energies show variation in the plasmon energy in hydrogenated carbon films. These changes were interpreted as a variation in the bonding nature of the sample with depth. The spectra of all samples were analyzed to determine ${\mathit{sp}}^2$/${\mathit{sp}}^2$+${\mathit{sp}}^3$ fraction, dielectric functions, and optical band gap.

• Received 29 March 1993

DOI:https://doi.org/10.1103/PhysRevB.48.12123