Samples were irradiated with 2.3MeV electrons or 60Co γ-rays. In the case of the electron irradiation, positron annihilation and optical absorption showed that 30 to 35% of the monovacancies (positron lifetime of 145ps) were removed by interstitials between 700 and 1020K. Above 1020K, divacancies were formed; giving rise to TH5 optical absorption and a positron lifetime of 185ps. Above 1120K, the TH5 absorption was replaced by absorption at 507/517nm, but no change in the positron lifetime was observed. The annealing of the γ-irradiated type-Ib samples differed substantially from that of the electron-irradiated samples, in that 60% of the monovacancies were removed between 350 and 525K.

Annealing of Monovacancies in Electron and γ-Irradiated Diamonds. S.Dannefaer, A.Pu, V.Avalos, D.Kerr: Physica B, 2001, 308-310, 569-72