Diamond crystals from Peoples Republic of China: An electron spin resonance and cathodoluminescence experimental study

Electron spin resonance (ESR) and cathodoluminescence (CL) evidence on diam onds from the Peoples Republic of China is reported. In addition to paramag netic centers P1 and P2 that had been observed in China diamonds, the W7, W 21, N2, OK1, and O1 centers were identified by ESR spectra for the set of s amples studied. The last two centers are regarded as oxygen-bearing. In the CL spectra, in addition to broad bands at 440 and 530 nm (the latter being related to boron centers), narrow bands were observed at 503 nm with phono n repetitions (H3 center), 415 nm (P2 ESR center), 575 nm, and 490.7 nm, as well as broad peaks at 720 and 920 nm. Characteristic narrow peaks were fr equent on the background of the 720-nm broad peak; their appearance in synt hetic diamond is assigned to the presence of nickel. An analysis of the app earance and behavior of the centers that are observable in ESR and CL spect ra showed a correlation between the type of defect, its concentration, and abundance, on one hand, and the crystal morphology, mineralogy, and geochem istry of the diamond, on the other. The ESR and CL characteristics of diamo nds from various China deposits provide grounds to believe that the combina tion of these parameters would aid in distinguishing diamonds from differen t pipes. In some cases, this spectroscopic evidence would substantially rev ise the prior genetic and geochemical ideas that were based on IR spectra a nd CL patterns only and would make them more exact.