Density functional theory modelling was used to predict electron energy-loss spectra (carbon K edges) at the spiro-interstitial position, and contrast those to bulk predictions. It was observed that, for a so-called bulk-like position in the spiro-interstitial model, the carbon K edge shape was similar to that of true bulk, thus confirming the validity of the model used. For the carbon K edge prediction at the spiro-interstitial position, although peaks in the π* region remain in approximately the same energy positions, there was considerable broadening suggesting the presence of strained sp2 bonding character. The σ* peak was significantly altered, both in energy position and intensity relative to the π* region. These observations were arguably consistent with a spiro-interstitial strained from the ideal bonding angles observed in spiro-pentane. Simulations of TEM and HAADF images of the spiro-interstitial model were also performed. These suggested that in a typical TEM, for the (100) orientation, even at a thickness of ~15Å the interstitial would be difficult to observe. In the case of (S)TEM, a similar situation exists.

Electron Microscopy of Nuclear Graphite: a Modelling Approach. C.R.Seabourne, R.Brydson, M.I.Heggie, C.D.Latham, A.J.Scott: Journal of Physics - Conference Series, 2012, 371[1], 012061