Paramagnetic defects in solid sulphur and glasses of the system Ge-S

Ge-S glasses are synthesised by melting pure S and Ge elements. Electron paramagnetic resonance (EPR) spectroscopy is used to analyse the paramagnetic defects in these glasses. Paramagnetic defects are also observed in amorphous and polycrystalline S samples after UV irradiation at T=77 K. The simulation of the EPR spectra leads to spectroscopic parameters of the sulphur centres which are similar in S samples and in S-rich Ge-S glasses, at the liquid nitrogen temperature. In Ge-S glasses, the paramagnetic sites remain stable at room temperature and the spectroscopic parameters are modified. The nature of the sites involved in these absorptions is discussed.