The mechanisms of formation of induced intrinsic and impurity radiative states, which consist of intrinsic and impurity electron–hole-trapping center states in irradiated and phosphates, were investigated using thermoactivation and vacuum-ultraviolet spectroscopy methods. These centers are excited at photon energies of 4.0 eV and 4.5 eV, which are within the matrix’s transparency region. New radiative-induced states at 3.06 eV and 2.92 eV are demonstrated to be generated upon the excitation of anions by photons with energies of 5.0 and 5.64 eV. This process is due to charge transfer from the ion to the impurities, specifically and the neighboring ion . Furthermore, upon the excitation of matrix anions with photon energies exceeding the band gap (8.0–8.25 eV), electron-trapping by impurities such as and ions results.
In this work, the mechanisms for creating a combined electronic–radiative local state beneath the conduction band, consisting of intrinsic and activator electron–hole states, are experimentally substantiated. In the first part of this work, the mechanisms of the formation of intrinsic and activator electron–hole trapping centers are experimentally demonstrated in all four matrices with activators. Intrinsic electronic states are localized on activators and anions of the matrix, forming intrinsic and activator electronic states. The hole component of the electron–hole pairs is localized near the activators. Thus, the energy of intrinsic electronic excitations localized in the matrix in the form of combined electronic–radiative states is observed at 3.06–3.1 eV and 2.92–2.95 eV. Radiative states are excited by photon energies of ~4.5 eV and ~4.0 eV, resulting in recombination emissions at 3.06–3.1 eV and 2.92–2.95 eV, as well as activator emissions at 2.06 eV for , 2.5 eV for , and 2.56 eV and 2.16 eV for . Energy transfer from the matrix to emitters or activators occurs during the decay of the combined radiative state. Upon heating, electrons localized on anions and activators delocalize at temperatures of 200–350 K. The energy released during the recombination of an electron with a hole near the activators is transferred to the activators. This process facilitates energy transfer to activators in dosimeters and detectors.
The mechanisms of formation of induced intrinsic and impurity radiative states, which consist of intrinsic and impurity electron-hole trapping centers in irradiated Ca2P2O7-Mn and Ca2P2O7 phosphates, were investigated using thermoactivation and vacuum-ultraviolet spectroscopy methods. These centers are excited at photon energies of 4.0 eV and 4.5 eV, which are within the matrix's transparency region. New radiative induced states at 3.06 eV and 2.92 eV are demonstrated to be generated upon the excitation of anions by photons with energies of 5.0 and 5.64 eV. This process is due to charge transfer from the ion to the impurities, specifically Mn^2+ O^2- Mn^2+ and the neighboring ion O^2- (P2O7)^4-. Furthermore, upon the excitation of matrix anions with photon energies exceeding the band gap (8.0 - 8.25 eV), electron trapping by impurities such as Mn^2+ and (P2O7)^4- ions results.
This study of the BaSO4-Bi phosphor has revealed that the accumulated energy after external optical excitation exhibits specific characteristics. During irradiation with photon energy exceeding the bandgap, in addition to the intrinsic ultraviolet emission of the Bi3+ ion, several recombination emissions and emission from the Bi2+ ion are observed. At 80 K, the recombination luminescence states and Bi2+ ion emission form combined electronic states. Upon heating of the BaSO4-Bi phosphor, these combined electronic states decay into recombination emissions at 2.34 eV, 2.4 eV, 3.1 eV, and 2.7 eV, as well as Bi2+ ion emission at 1.97 eV. It is assumed that the 2.34 eV, 2.4 eV, and 3.1 eV emissions are associated with the recombination of electrons released from ionized electron trapping centers with nonequivalently localized holes in the host lattice. The 2.7 eV emission is attributed to the decay of an exciton formed by electron–hole recombination near a Bi3+ ion.