ABSTRACT
Electron paramagnetic resonance of mantle derived IIa type diamonds from Finsch pipe, South Africa, and diamonds from the impact craters of Nördlinger Ries, Germany, and Popigai, Russia, were studied. Generally the crystals from Finsch pipe exhibited a relatively weak fine structure (FS) line as well as weak superhyperfine splittings of the P1 and P2 type, whereas the diamonds from the impact areas revealed a relatively strong FS line only, P1 and P2 lines being apparently absent. The results hint to differences in the amount of N substitution for C and “dangling” bonds depending on speed of crystal growth associated with mantle or shock wave processes.
