Interpretation of Raman spectra of disordered and amorphous carbon
نویسندگان
چکیده
The model and theoretical understanding of the Raman spectra in disordered and amorphous carbon are given. The nature of the G and D vibration modes in graphite is analyzed in terms of the resonant excitation of p states and the long-range polarizability of p bonding. Visible Raman data on disordered, amorphous, and diamondlike carbon are classified in a three-stage model to show the factors that control the position, intensity, and widths of the G and D peaks. It is shown that the visible Raman spectra depend formally on the configuration of the sp sites in sp-bonded clusters. In cases where the sp clustering is controlled by the sp fraction, such as in as-deposited tetrahedral amorphous carbon ~ta-C! or hydrogenated amorphous carbon ~a-C:H! films, the visible Raman parameters can be used to derive the sp fraction.
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