Energy Transfer in the CaSO4−Dy Thermoluminescent Dosimeter from the Excited State of the SO2− 4 Anionic Complex to the Impurities

Abstract

The creation of a combined radiative state at 2.95–3.1 eV in the phosphor CaSO4 − Dy3+ has been investigated using vacuum ultraviolet and thermoactivation spectroscopy methods. It is shown that the combined radiative electronic state is formed from the radiative electronic states of the impurity electronic trapping centers Dy2+ − SO− 4 and the intrinsic electronic radiative states SO3− 4 − SO− 4 during the excitation of the anion complex SO2− 4 , as a result of charge transfer from the excited anion complex O2− − Dy3+ to the impurities and the neighboring anion complex O2− − SO2− 4 . In the CaSO4 − Dy phosphor, the combined radiative electronic state and impurity emission of Dy3+, 2.16 eV and 2.56 eV are excited by photons with energies of 3.95–4.0 eV and 4.5–4.6 eV. Energy transfer from the matrix to the Dy3+ impurities is revealed upon thermal exposure as a result of the ionization of the electronic capture centers of Dy2+ and SO3− 4 .