Photoluminescence studies of the 523.7 nm optical centre in HPHT synthetic diamond

The 523.7 nm centre is very commonly observed in electron irradiated HPHT synthetic diamond, but not in CVD samples with high N content up to 50 ppm. Absorption studies indicated that the 523.7 nm centre was caused by nitrogen-interstitials complexes, and this hypothesis was supported by the insensitivity of its zero phonon line to stress. However, its high annealing temperature, strong broad phonon sideband and lack of high energy local vibrational modes suggest that the 523.7 nm centre was more probably vacancy-related.

► The 523.7 nm centre is very common in electron-irradiated high N diamonds.
► There are remarkable differences between absorption and emission results.
► No clear evidence about the natural structure was found for this centre.