Electron spin resonance of excited states of the H3 and H4 centres in irradiated type Ia diamonds

Abstract

Electron spin resonance spectra, denoted W26 and W25, observed in type Ia diamonds showing the H3 and H4 optical absorptions, respectively, are shown to be due to excited states of the defects responsible for these absorptions. Zero-field and hyperfine parameters have been determined and are presented in this paper. The models proposed earlier by Loubser and van Wyk for the H4/W25 defect, and thus by extension also for the B nitrogen aggregate, are confirmed by the present work. The ESR results also support the the model proposed by Davies for the H3 centre.