Characterization of nanocrystalline diamond films by core-level photoabsorption

Core-level photoabsorption has been used to determine the sp2 and sp3 bonding content of nanocrystalline diamond thin films grown using C60 or CH4 precursors. The C(1s) absorption spectra show clear bulk diamond excitonic and sp3 features with little evidence of sp2 bonding, while the Raman spectra measured from these same films are ambiguous and indeterminate. This result can be attributed to the local structure (near-neighbor bonding) sensitivity of core-level photoabsorption that is insensitive to domain size, unlike Raman spectroscopy.