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The mechanisms of formation of induced intrinsic and impurity radiative states, which consist of intrinsic and impurity electron–hole-trapping center states in irradiated C a 2 P 2 O 7 − M n and C a 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 M n 2 + (O 2 − − M n 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 M n 2 + and (P 2 O 7 ) 4 − ions results. [ABSTRACT FROM AUTHOR]

The creation of a combined radiative state at 2.95–3.1 eV in the phosphor C a S O 4 − D y   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 D y   2 + −   S O 4 − and the intrinsic electronic radiative states S O 4 3 − − S O 4 − during the excitation of the anion complex S O 4 2 − , as a result of charge transfer from the excited anion complex O   2 − − D y   3 + to the impurities and the neighboring anion complex O 2 − −   S O 4 2 − . In the C a S O 4 − D y phosphor, the combined radiative electronic state and impurity emission of D y   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 D y   3 + impurities is revealed upon thermal exposure as a result of the ionization of the electronic capture centers of D y 2 + and S O 4 3 − . [ABSTRACT FROM AUTHOR]

Vacuum ultraviolet and thermal activation spectroscopies were used to study the nature of intrinsic emission and the mechanisms of the formation of electron and hole trapping centres in irradiated Li2SO4 powders and crystals. The obtained results along with excitation spectra showed that recombination emission at 3.8–4.2 eV and 4.5–5.5 eV occurs when an electron passes from the second and third sub-bands of the valence band formed from the 2p state of oxygen to the conduction band. It has been determined that Li2SO4 electron and hole trapping centres are created when electrons are trapped in the SO42– anionic sites. The holes are localised in the form of SO4 – radicals. The spectral position and intensity of individual emission bands are dependent on the crystallographic arrangement of localised holes. [ABSTRACT FROM AUTHOR]

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Spectroscopic and thermoactivation methods were used to study the processes of accumulation of electron and hole trapping centers and energy transfer of electronic excitations to impurities in C a S O 4 - M n and B a S O 4 - M n . It is shown that electronic trapping centers are created during the excitation of an anionic complex as a result of charge transfer from O 2 − → S O 4 2 − to closely spaced anionic complexes S O 4 2 − in C a S O 4 and B a S O 4 . In C a S O 4 and B a S O 4 , energy transfer from the host to impurities occurs at the moment of charge transfer from the excited anionic complex to the combined radiative electronic state at 2.95–3.1 eV. This combined state is formed from electronic trapping centers M n + - S O 4 − and S O 4 3 − - S O 4 − . It was found that the emerging combined radiative states at 2.95–3.1 eV of sulfates, which are formed as a result of charge transfer from the excited anionic complexes to the excited state of impurities, T l + , C u + , a n d   M n 2 + , occupy the same energy levels as the intrinsic electronic trapping center S O 4 3 − of the host at 2.95–3.17 eV. Experimental results show that during UV photon irradiation, anionic complexes are excited mainly near impurities in sulfates. [ABSTRACT FROM AUTHOR]

This article describes a new technique for postsynthetic doping/alloying of Mn into ZnSe nanocrystals. The key feature is that it employs diethyldithiocarbamate anion to selectively bind the host cations and promote ion exchange. The presence of Mn in the product is confirmed with photoluminescence (PL) and total reflection X‐ray fluorescence spectroscopy. The cation exchange reaction takes place at temperatures as low as 100 °C. Higher temperatures allow to incorporate the impurity in greater quantities; however, after a crossover temperature of ≈200 °C, the process gets convoluted with Ostwald ripening and sulfide deposition, as evident from electron diffraction data, high‐resolution transmission electron microscopy (HR‐TEM), and elemental analysis of the samples. Studies of PL lifetime and quantum yield confirm these findings. Preliminary success is also shown for other impurities: Fe and Co are present in the respective samples in ≈17 at% of total metal content. [ABSTRACT FROM AUTHOR]