The structure and dynamics of the interstitial O dimer were deduced by using a combination of infra-red spectroscopy and ab initio modelling. It was found that the stable dimer consisted of a pair of inequivalent weakly-coupled interstitial O atoms that were separated by a Si-Si bond. Two high-frequency modes were decoupled in one 16O-18O combination, but were strongly mixed in the other combination. A third lower-lying mode involved compression of the Si-Si bond which joined the O atoms, and generated distinct modes in the mixed 16O-18O case.

First stage of oxygen aggregation in silicon S.Oberg, C.P.Ewels, R.Jones, T.Hallberg, J.L.Lindström, L.I.Murin, P.R.Briddon: Physical Review Letters, 1998, 81[14], 2930-3