Synthetic diamond identification under X-ray excitation

Phosphorescence is a basic luminescence phenomenon that is repre-sented by continuous light emission for a period after materials have absorbed excitation energy. Here, an obvious blue-green long phos-phorescence is observed in some fluorescence areas of diamond wa-fers synthesized by high-pressure and high-temperature (HPHT) methods following X-ray excitation. Based on these results, we show that the blue-green fluorescence and long phosphorescence have contributions from two kinds of luminescence centers near the same emission wavelength (-500 nm) in an HPHT diamond, i.e., the transition of the internal energy level of iron (Fe) under par-ity conservation rule and radiative recombination of nitrogen-boron donor-acceptor pair with the assistance of phonons. This study may help to inspire a deeper understanding of the long phosphores-cence of wide-band-gap inorganic materials, and it also provides a possible and effective means of distinguishing between artificial and natural diamonds under X-ray radiation.