Radiation damage produced by 0.4-2.0 MeV electrons in diamond

The spectroscopic properties of the main radiation-induced optical absorption spectrum (GR system) in diamond are discussed. This includes a discussion of the local symmetry and of the relation of the defect energy levels to the diamond energy bands. The stability of the centre is also considered and this is crucial in the assignment of the vacancy to the GR system. The room-temperature-stable ESR centres and those formed at higher temperatures are reviewed and can be seen to fit into a consistent scheme. This scheme requires that the interstitial be mobile at about 100 K and therefore the low-temperature irradiation experiments are reviewed. They are not completely clear-cut but there is evidence of a defect mobility at about 100 K and of a further defect which is stable for temperatures up to 250 to 300 K. (author)