Investigation of TLD Phosphors by Optical Excitation –Luminescence of Eu²⁺Centers in MgSO₄, CaSO₄, SrSO₄, BaSO₄–

Abstract

The photoluminescence (PL) and excitation spectra of various thermoluminescence dosimetry (TLD) phosphors were measured at temperatures of 6, 17, 80 and 300 K. Their PL spectra at 300 K consist of a single band in the vicinity of 380 nm. The emission bands and their excitation bands are ascribed to the electronic 4 f 6 ·5 d ↔4 f 7 transitions in the Eu 2+ ions. In the PL spectra of MgSO 4 :Eu 2+ , SrSO 4 :Eu 2+ and BaSO 4 :Eu 2+ , the emission lines due to the electronic 4 f 7 →4 f 7 transition in the Eu 2+ ion were also observed near 360 nm, in addition to the broad band. No line emission due to the Eu 3+ center was observed in any of the phosphors prepared in the present work. In CaSO 4 :Eu 2+ cooled to low temperatures, phonon structures are observed on the emission band and the low-energy excitation band. The TL emission spectra of BaSO 4 :Eu 2+ at various temperatures were also measured.