科研之友
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摘要
A series of carbon nitride structures have been generated, by using a classical potential in a Metropolis Monte Carlo liquid quench procedure. The resulting structures are relaxed further using the density functional theory approach. Structures are generated for various mass densities and varying N/C ratio so that all possible C-N bonding configurations are produced. Structural analysis of the equilibrated structures are performed and the effect of nitrogen inclusion on the formation of curved carbon systems is evidenced. Density of states and energy-loss near-edge structure calculations show that nitrogen incorporation modifies the valence and conduction bands of amorphous carbon (a-C). X-ray photoelectron spectroscopy (XPS) calculations within the first-principles methodology are also performed on the generated a-C nitride systems. Depending on the carbon bonding configuration, the carbon 1 s energies are found to vary from 283 eV to 288 eV while those of nitrogen are found to range from 397 eV to 402 eV. The experimentally observed N 1 s XPS features of a-C nitride systems are correlated with the nitrogen bonding state with carbon, the degree of delocalization of the nitrogen lone pair and the C-N bond length. In particular, our calculations support the interpretation of the N is feature at an energy of about 398.4 eV to two-coordinated N atoms whose immediate neighbors enhance a delocalization of the N lone pair of electrons.
- 出版日期2006-9
