High-resolution luminescence-excitation spectra of the GR defect in diamond

Abstract

Luminescence-excitation spectra of the GR defect have been recorded at high resolution for an irradiated natural semiconducting diamond. Luminescence produced in the GR1 region was monitored while the wavelength of the exciting radiation was scanned over the GR1 and GR2-8 absorption systems and part of the ultraviolet continuum. All the GR2-8 lines observed in absorption are faithfully reproduced in the excitation spectrum, showing that the centre relaxes via the first excited state (GR1). Luminescence measurements have shown that the relaxation to the first excited state is nonradiative. The lines are weaker in the excitation spectrum than in the absorption spectrum, and this is consistent with the fact that they may also be observed by photoconductivity measurements. In addition, the results show that there is absorption underlying what is normally regarded as the GR1 absorption band that does not give rise to GR1 luminescence.