The origin of electron trapping and negative charging of hydroxylated silica surfaces was predicted based on accurate quantum-mechanical calculations. The calculated electron affinities of the 2 dominant neutral paramagnetic defects, the non-bridging O center, ≡Si-O•, and the Si dangling bond, ≡Si•, demonstrated that both defects were deep electron traps and could form the corresponding negatively charged defects. The structures and optical absorption energies of these diamagnetic defects were predicted.

Electron Trapping at Point Defects on Hydroxylated Silica Surfaces. L.Giordano, P.V.Sushko, G.Pacchioni, A.L.Shluger: Physical Review Letters, 2007, 99[13], 136801