Spectroscopy of π bonding in hard graphitic carbon nitride films: Superstructure of basal planes and hardening mechanisms

Abstract

X-ray-absorption near-edge spectroscopy ͑XANES or NEXAFS͒ has been used to obtain information on the orientation, corrugation, and cross-linking of graphitic carbon nitride planes, structural parameters that determine the mechanical properties of the material. The contribution of p electrons from carbon and nitrogen atoms to bonding in graphitic carbon nitride has been studied with elemental and angular sensitivity by XANES. The density of * states from nitrogen is composition dependent and presents angular anisotropy, while the density of * states from carbon is isotropic and independent of composition. Both observations are consistent with a model of the superstructure of basal planes.

X-ray absorption of nitrogen-doped amorphous carbon films for determining sp2/sp3 bonding concentrations

“…These studies report various amounts of sp 2 hybridization, but suggest that p* resonances are expected up to approximately 4.5 eV above the initial onset of C 1s to 2p absorption. For the a-C samples in this study, features with center positions energetically below and at 288.5 eV are labeled p* resonances, which is also in accordance with several authors (Lenardi et al, 1999;Jimenez et al, 2000;Bhattacharyya et al, 2002;Broitman et al, 2003). The IP onset lies at 289 eV for a-C films (Terminello et al, 1991;Carravetta et al, 1995).…”

Core level spectra of amorphous carbon nitride

“…[13][14][15][16][17] A clear correlation of N 1s x-ray absorption and photoemission spectra has been observed in the particular case of amorphous carbon nitride. 13,16 The physical origin of this correlation seems to be the large initial state effects ͑charge shifts, which affect both XAS and XPS spectra in the same way͒, while final state effects ͑which are different for XAS and XPS spectra͒ are almost an order of magnitude smaller.…”

Enhanced tunnel transport in disordered carbon superlattice structures incorporated with nitrogen

“…From the near edge x-ray photoelectron fine structures (NEXAFS) of a À CN films, the effect of disorder for C and N edges can be clearly seen. 34 By annealing these films, the disorder associated with C and N sites can be controlled as observed from NEXAFS spectroscopy. 33 The change of resistance of nitrogen-rich CN films was found with the annealing temperatures, which can be explained by thermally assisted rearrangement of C and N atoms within the structures.…”

“…On the other hand, experimentally a separate (N) peak has been found to be difficult to identify from disordered C À N structures. [32][33][34][35][36] This happens not only due to the low N percentage but also due to large disorder introduced in the carbon structures by incorporating a high amount of nitrogen as shown in Fig. 8.…”