Revisiting the determination of carbon sp2/sp3 ratios via analysis of the EELS carbon K-edge

Carbon materials are highly versatile owing to the strong dependence of their physical properties on the ratio of sp2 (graphitic) to sp3 (adamantine) bonds. Graphitic carbons have a variety of forms with various degrees of ordering ranging from microcrystalline graphite to glassy carbons. Amorphous carbons can have any mixture of sp3, sp2 and, in some cases, sp1 bonded carbon sites with the additional possible presence of hydrogen, nitrogen or boron. The structure of amorphous or poorly crystalline carbon materials are difficult to study using conventional characterisation tools; techniques which have been successfully applied include neutron scattering, nuclear magnetic resonance, (uv) Raman spectroscopy and EEL