Some properties of the visible luminescence excited in diamond by irradiation in the fundamental absorption edge

Abstract

The properties of the visible (“blue band” or “band A”) luminescence, which is excited in natural and synthetic diamond by electromagnetic radiation of quantum energy near to the fundamental absorption edge and also by energetic charged particles, are contrasted with those of the better known visible luminescence systems (4150, 4968, 5030, 5755 Å series etc.). The effects of temperature, external electric and magnetic fields and irradiation damage produced by 500 keV electrons are discussed and tentatively interpreted in terms of a process in which secondary energy is transferred to the band A emission centres by excitons and electron-hole pairs. The temperature dependence of the integrated intensity and the decay time of the band A luminescence is shown to be consistent with a configurational co-ordinate description of the energy levels of the emission centre. The radiative decay time of the excited state is ∼ 10 −2 sec at 80°K. Above ∼ 100°K, a radiationless de-excitation process is observed with a thermal activation energy of 0.36 ± 0.02 eV.