ODMR and optical investigations of vacancies in MPS3 lattices

Photoluminescence from lamellar chalcogenide lattices of CdPS3 and ZnPS3 has been examined using the techniques of photoexcitation, photoluminescence and optically detected magnetic resonance (ODMR) spectroscopy. Sharp absorption edges are observed at 3.295 and 3.50 eV in the ZnPS3 and CdPS3 lattices respectively. The band edge of ZnPS3 is about 1 eV higher in energy than previously reported and in agreement with recent band structure calculations. Peaks below the band edge due to stacking disorder were noted. A nearly isotropic ODMR signal without resolved nuclear hyperfine splittings is observed from CdPS3 after intercalation with pyridine. The signal is analyzed in terms of weakly exchange coupled donor and acceptor centers with g = 2. ZnPS3 crystals exhibit a complex, angle dependent ODMR spectrum prior to intercalation. The ODMR spectrum arises from a strongly coupled, two electron triplet center. Signals were associated with luminescence that is due to octahedral zinc vacancy centers in ZnPS3. The system was modeled as two strongly coupled electron spins with hyperfine interaction due to a nearby I = 1/2 31P nucleus. Photoluminescence spectra of fullerenes C60 and C70 are reported, for both microcrystalline solids and glassy solutions. Tentative analyses for the solution spectra are presented