Evidence for the existence of nitrogen-substituted graphite structure by polarization dependence of near-edge x-ray-absorption fine structure

The electronic structure of carbon nitride (CNx) film produced by low-energy ion implantation has been studied by N Is near-edge x-ray-absorption fine structure (NEXAFS). The NEXAFS spectra of CNx film have shown three sharp pi* and one broad sigma* resonances whose intensities have clear polarization dependence. The polarization dependencies of the first and third pi* resonances have given a similar tendency to that of the pi* resonance of graphite, while the second pi* resonance has given different behavior. From the results, we concluded that the first, second, and third pi* resonances originate from pyridinelike structure, cyanic structure, and graphitelike structure, respectively. The results show the clear experimental evidence that there exists a graphitelike structure in which some of the carbon atoms are substituted by nitrogen atoms.