The creation of a combined radiative state at 2.95–3.1 eV in the phosphor ${CaSO}_4-{Dy}_{ }^{3+}$ 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 ${Dy}_{ }^{2+}-{ SO}_4^{-}$ and the intrinsic electronic radiative states ${SO}_4^{3-}-{SO}_4^{-}$ during the excitation of the anion complex ${SO}_4^{2-}$, as a result of charge transfer from the excited anion complex $O_{ }^{2-}-{Dy}_{ }^{3+}$ to the impurities and the neighboring anion complex $O^{2-}-{ SO}_4^{2-}$. In the ${CaSO}_4-Dy$ phosphor, the combined radiative electronic state and impurity emission of ${Dy}_{ }^{3+}$, 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 ${Dy}_{ }^{3+}$ impurities is revealed upon thermal exposure as a result of the ionization of the electronic capture centers of ${Dy}^{2+}$ and ${SO}_4^{3-}$.

Quantum-confined CdTe nanoplatelets (NPL) are synthesized in colloidal solutions. The formation, growth, and transformation of 2D NPLs are monitored using UV-visible absorption PL spectroscopy and transmission electron microscopy. The luminescence intensity of NPL dependences on the temperature and injection of precursors is shown. It is found that the luminescence spectra shift to the long-wavelength region with increasing temperature due to an increase in the thickness of the NPL. The dependence of the band gap on the thickness of the NPL is shown. The band gap is determined by the thickness and number of layers. The dependence of the concentration of precursors in the reaction mass and the kinetics of NPL growth are shown. The excitation of defect states luminescence depends on the coordinating oleic ligand. The crystal structure of the CdTe NPL was analyzed via the electron diffraction pattern (ED), which allows a comparative conclusion about the crystal structure of the obtained NPL samples.

Colloidal quasi-two-dimensional cadmium chalcogenide nanoplatelets have attracted considerable interest due to their narrow excitonic emission and absorption bands, making them promising candidates for advanced optical applications. In this study, the synthesis of quasi-two-dimensional CdSe NPLs with a thickness of 3.5 monolayers was investigated to understand the effects of synthesis temperature on their stoichiometry, morphology, and optical properties. The NPLs were synthesized using a colloidal method with temperatures ranging from 170 °C to 210 °C and optimized precursor ratios. Total reflection X-ray fluorescence (TXRF) analysis was employed to determine stoichiometry, while high-resolution transmission electron microscopy (HRTEM) and UV-Vis spectroscopy and photoluminescence spectroscopy were used to analyze the structural and optical characteristics. The results showed a strong correlation between increasing synthesis temperature and the enlargement of nanoscroll diameters, indicating dynamic growth. The best results in terms of uniformity, stoichiometry, and optical properties were achieved at a growth temperature of 200 °C. At this temperature, no additional optical bands associated with secondary populations or hetero-confinement were observed, indicating the high purity of the sample. Samples synthesized at lower temperatures exhibited deviations in stoichiometry and optical performance, suggesting the presence of residual organic compounds.

The mechanisms of formation of induced intrinsic and impurity radiative states, which consist of intrinsic and impurity electron–hole-trapping center states in irradiated ${Ca}_2{P}_2{O}_7-Mn$ and ${Ca}_2{P}_2{O}_7$ 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 $O_{ }^{2-}-(P_2{O}_7{)}^{4-}$. 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 $(P_2{O}_7{)}^{4-}$ ions results.