We present a technique to determine the sp3/sp2 ratio of carbon materials which is based on the electron energy-loss spectroscopy and which uses the theoretical spectrum of graphite obtained from ab initio electronic structure calculations. The method relies on the separation of the π∗ and σ∗ components of the carbon K-edge of graphite. This π∗ spectrum is adopted and assumed to be transferable to other carbon systems given an appropriate parametrisation of the broadening. The method is applied on a series of Monte-Carlo generated amorphous carbon structures and is shown to be stable over a wide range of the energy windows for which spectral integration is performed. The results are found to be in good agreement with the sp3 fraction obtained from a microscopic scheme which uses the π−orbital axis vector (POAV1) analysis. The technique was also applied on a series of experimental spectra of amorphous carbon and was found to be in good agreement with the results obtained from a functional fitting approach.
@article{arxiv.cond-mat/0310358,
title = {A new technique for the sp$^2$/sp$^3$ characterisation of carbon materials},
author = {J. Titantah and D. Lamoen},
journal= {arXiv preprint arXiv:cond-mat/0310358},
year = {2009}
}
Comments
5 pages, 4 figures, two tables revtex4, Submitted for publication to Phys. Rev. Lett