The segregation of nickel-related optical centres in the octahedral growth sectors of synthetic diamond

Abstract

The vibronic absorption bands with zero-phonon lines at 1·40, 1·883, and 2·51 eV, the broad absorption band with a maximum near 1·4eV and the series of absorption lines near 3·1 eV, the vibronic luminescence bands with zero-phonon lines at 1·40eV and 2·56 eV, all associated with nickel-related optical centres in synthetic diamond, are shown in this investigation to be restricted exclusively to the octahedral growth sectors. In addition, absorption in a sharp line at the Raman frequency (1332cm⁻¹), at the high-frequency limit of the defect-induced one-phonon region, is present only in the octahedral sectors. The relative intensities of the different absorption bands depend on the nitrogen concentration in the diamond. The 1·883 and 2·51 eV systems are strongest in samples containing a high nitrogen concentration, whereas the 1·4 eV broad band and 1·40 eV vibronic system are strongest in diamonds with a low nitrogen concentration.