PHOTOLUMINESCENCE AND ODMR STUDIES OF LAMELLAR CD2P2S6 AND ZN2P2S6 LATTICES

Photoluminescence, photoexcitation, and optically detected magnetic re sonance (ODMR) spectroscopy have been used to characterize the band ga p defect states of native and intercalated lattices of two lamellar ch alcogenophosphate materials, Cd2P2S6 and Zn2P2S6. Native Zn2P2S6 cryst als exhibit a complex, angle-dependent ODMR spectrum that is interpret ed as arising from lattice metal vacancies. Upon UV irradiation below 4 K, the zinc vacancies trap two photoexcited holes to yield a localiz ed S = 1 photoexcited triplet with zero-field splitting parameters \D\ = 15.875 GHz and \E\ = 5.175 GHz. A nearly isotropic ODMR signal with out resolved nuclear hyperfine splittings is observed from Cd2P2S6 aft er intercalation with pyridinium cations. The signal is analyzed in te rms of weakly exchange coupled donor and acceptor centers with g appro ximate to 2.