Synthetic diamond identification under X-ray excitation
Lu Cheng, Yanming Zhu, Richeng Lin, Ying Ding, Xiaoping Ouyang, Wei Zheng
Abstract
Phosphorescence is a basic luminescence phenomenon that is represented by continuous light emission for a period after materials have absorbed excitation energy. Here, an obvious blue-green long phosphorescence is observed in some fluorescence areas of diamond wafers 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 parity 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 phosphorescence 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.