In the pursuit of novel bactericidal solutions, there has been a significant advancement in the development of phosphors emitting ultraviolet C (UVC) radiation, intending to supplant mercury lamps in healthcare settings. Moreover, these innovative phosphors hold promise for treating X-ray-resistant tumors and disinfecting water in regions with limited access to electricity. In this study, a new UVC emitter, LiNaY2F8, doped with Pr3+ ions, is introduced. The paper comprehensively examines the structural and optical properties of the material, utilizing visible (Vis),vacuum ultraviolet (VUV), and X-ray spectroscopy techniques.The presence of distinct crystallographic sites for Pr3+ ions is demonstrated, and a potential mechanism is proposed for the simultaneous emission from the 4f15d1 and 1S0 levels of Pr3+. Furthermore, successful Vis-to-UVC upconversion in this host material is reported. UVC emission at approximately 250nm was observed under 444nm laser excitation. The power dependence analysis revealed that two photons of blue light are required to observe the upconversion. Additionally, the decay kinetics analysis of the upconversion luminescence suggests excited state absorption (ESA) as the most plausible mechanism for the upconversion process. Finally, the scintillating properties of the material are confirmed, with both UVC and visible luminescence detected upon X-ray excitation. This study introduces the newly synthesized luminophore, highlights its favorable optical characteristics for converting visible light or X-ray radiation into UVC, and emphasizes its potential multifunctional applications.

In this paper, the effect of Yb dopant on the optical and photoelectric properties of CsPbCl3:Yb single crystals is studied. The position of the main energy level of Yb3+ ions relative to the energy band was determined. Two channels of electron photoionization into the conduction band were identified, which are photo-stimulated transition of valence electrons and transition of electrons from the ground level of the Yb3+ dopant ion. The crucial role of Yb2+ ions in the manifestation of the quantum cutting effect was shown. A non-uniform distribution of ytterbium dopant in the CsPbCl3:Yb single crystal volume was revealed. It was established that the absolute quantum yield of ytterbium luminescence in CsPbCl3:Yb single crystals in the near-infrared region at Yb concentration of 2 mol.% reaches 86%.

The search for and fabrication of materials for the near-infrared range of the spectrum, including telecommunication windows, is an extremely important task in modern technology. This work presents the results of studies on the photoluminescence of CsPbCl3 single crystals with varying contents of ytterbium and erbium impurities, grown using the Bridgman method. The existence of electrically neutral Yb3+-V-Pb-Er3+ complexes within the crystal structure was confirmed. Resonant absorption of excitation radiation lambda = 980 nm by Yb3+ ions reveals a three-step energy transfer channel from Yb3+ to Er3+ ions within a single complex. The estimated quantum yield of up-conversion luminescence at lambda = 524 nm (0.02%) associated with erbium ions indicates the presence of electronic transitions to higher energy levels, with the possibility of subsequent emission within the third telecommunication window.

The research investigates the spectral-luminescent properties of linseed oils obtained through cold pressing, depending on the storage duration under domestic conditions (in a refrigerator at 4 degrees C, in the absence of sunlight). We recorded a notable decline in the luminescence intensity bands of the oil components (tocopherols, polyunsaturated fatty acids, vitamins, pigments) alongside an escalation in the luminescence intensity of their oxidation products, correlating with the duration of oil storage under domestic conditions. Our findings indicate that prolonged oil storage (exceeding two years) results in the oxidation and degradation of phenols, tocopherols, polyunsaturated fatty acids (linoleic, linolenic, arachidonic), vitamins B-2 and E, precursor of vitamin A (carotene), chlorophyll pigment.

Cd2+ cation doped CsPbCl3 single crystals were synthesized, and their luminescent properties were investigated under excitation with synchrotron radiation quanta with energy greater than Eg and at a sample temperature of 12 K. Pure single crystals exhibit a narrow band of exciton emission at 416.7 nm. Doping the single crystals leads to a high-energy shift of the excitonic luminescence, the appearance of new luminescent bands, the broadening of the luminescent bands, an increase in the decay time constants, and a significant enhancement of the luminescence intensity. The observed changes in luminescent parameters upon doping are discussed in terms of the crystal structure ordering, a decrease in the number of defects responsible for capturing charge carriers at the stage of electronic excitation thermalization, and a decrease in defects that quench excitonic luminescence. Doped single crystals with decay times of the order of 0.4 ns and intensities that significantly exceed the intensity of pure single crystals can be promising scintillation materials for positron emission tomography in the time-of-flight mode.

The temperature dependences of the luminescence spectra for CsPbBr3 single crystal and nanoparticle ensemble are presented. The emission bands of single crystal are interpreted in terms of the direct and indirect exciton transitions. An attempt to estimate the contribution of the direct and indirect transitions for wide luminescence band inherent for CsPbBr3 nanoparticles is made. The temperature dependence of the luminescence band position is analyzed by the taking into account the thermal expansion and exciton-phonon interaction. For both the single crystal and the ensemble of nanoparticles, main contribution to the shift of the luminescence bands of the direct and indirect excitons to the low-energy region was revealed to be caused by the interaction with optical phonons. This interaction is predominant for the indirect excitons and can be used as a sign of Rashba nature of the exciton.

The spectral and luminescence properties of linseed oils with different background have been studied. High informativity of oil fluorophores (phenols, tocopherols, polyunsaturated fatty acids, vitamins, pigments) as to their native state depending on the influence of various destructive factors: extended storage period of oil (three years), exposure to sunlight for 50 h and contact with temperatures in the range of 60 ºC > t > 46 ºC was registered. It was revealed that:

A empty set40x90 mm CsCa0.95Eu0.05Br3 single crystal has been grown using the Bridgman-Stockbarger technique. Spectral-luminescent and scintillation properties of the specimens with different volume prepared from CsCa0.95Eu0.05Br3 are reported. The spectral-luminescent properties were studied upon excitation with X-rays at 77 K and 293 K and the scintillation properties were investigated using a(137)Cs gamma source. The effect of crystal surface treatment in achieving good energy resolution is discussed. The surface morphology of a fresh cleaved CsCa(0.95)Eu(0.0)5Br(3) crystal was studied and imaged with a scanning electron microscope in the cathodoluminescence mode.

Investigation of the spectral and luminescence characteristics of CsPbBr3 nanocrystals coated with poly (NVP-co-VEP-co-GMA) oligoperoxide molecules dispersed in a polymer matrix under excitation in the energy region of quanta E = 2 divided by 6 eV was carried out. Formation of CsPbBr3 nanocrystals dispersed in the polymer matrix has been confirmed by electron microscopy, X-ray diffraction and optical spectroscopy. Spectral structure and kinetic parameters of the luminescence of polymer-inorganic composites with dispersed CsPbBr3 nanocrystals are discussed considering possible influence of size effects on the relaxation processes of intrinsic electron excitations. The revealed temperature dependence of the luminescence intensity and of the spectral luminescent maximum position of bound exitons of these nanocrystals in the temperature range of 77 divided by 295 K promotes their use for temperature measurements of biological objects.

The single crystals of RbCa1−yEuyX3 (X = Cl, Br; y = 0.03, 0.05, 0.08) were obtained by the Bridgman–Stockbarger technique. The luminescent and luminescent-kinetic properties of RbCaCl3:5%Eu and RbCaBr3:5%Eu under photo- and X-ray excitation (35–40 keV) at 77 and 293 K were studied. The luminescence spectra of the crystals exhibit one dominant band which corresponds to Eu2+ emission. The scintillation properties of all the grown crystals under 137Cs 662 keV gamma-ray excitation were investigated. The maximal values of relative light output were found for RbCaCl3:8%Eu2+ and RbCaBr3:8%Eu2+ which are approximately equal to 50% and 77% of NaI:Tl with decay time 2.7 and 3.6 μs respectively. The hygroscopicity of the crystals was estimated.

The scintillation properties of RbCa1-xEuxCl3 (x = 0.005, 0.03, 0.05, 0.08) single crystals grown from the charge obtained by the solution routine using the Bridgman-Stock-barger method are reported. The luminescence spectra of RbCa1-xEuxCl3 crystals show a single band with a maximum which position shifts from 437 to 443 nm with increase of mole fraction of Eu2+ from 0.005 to 0.08. The decay of the scintillation pulse can be described using single component and the decay time rises towards concentration of Eu2+ in crystals. The relative light yield achieves 55 per cent vs. NaI:TI for RbCa0.92Eu0.08Cl3 sample.

Single crystals of new scintillation materials ACaBr3:Eu2+ (A = K, Rb) were grown using the Bridgman–Stockbarger method. The luminescence spectra of RbCa1‐xEuxBr3 crystals include a single band with a maximum which position shifts from 433 to 443 nm with the increase of mole fraction of Eu2+ from 0.005 to 0.08. The decay of the scintillation pulse can be described using single component and the decay time rises towards concentration of Eu2+ in crystals from 2.70 μs (x = 0.03) to 3.14 μs (x = 0.05). The relative light yield achieves 77 per cent vs. NaI:Tl for RbCa0.92Eu0.08Cl3 sample and the energy resolution is 8.2%. Comparing with the K‐based analogs RbCa1‐xEuxBr3 materials are more stable and they are considerably brighter scintillators than CsCa1‐xEuxBr3.

The current work describes two Eu2+-activated scintillation materials, K2BaCl4 and K2BaBr4. The single crystals of K2Ba1-yEuyX4 (X = Cl, Br, y = 0.005, 0.03 and 0.05) were grown using the Bridgman -Stockbarger method. The spectral -luminescent and luminescence -kinetic properties under the excitation by photo and X-ray quanta are studied. The scintillation properties of K2BaX4:Eu2+ (X = CI, Br) crystals have been investigated using a(137)Cs gamma source. The relative light yield increases with the Eu2+ concentration in K2BaX4:Eu2+. Moisture sensitivity of the crystals was evaluated and compared with Nal:Tl crystal.(C) 2017 Elsevier B.V. All rights reserved.

Luminescence-kinetic properties of LaI3-Ce microcrystals of 1-10 mu m size in NaI-LaI3-Ce system are studied upon 2.5-12 eV excitation using synchrotron radiation. The luminescent properties of cerium centers in the embedded LaI3-Ce microcrystals are revealed to be similar to those for the bulk LaI3-Ce crystals. The mechanisms of cerium centers luminescence excitation in the NaI-LaI3-Ce crystalline system upon excitation in the transparency and fundamental absorption range of NaI and LaI3 matrixes and mechanisms of thermal quenching of cerium ions luminescence in the LaI3 microcrystals are discussed.

Luminescence spectroscopy has been used to determine the parameters of NaI-SrI2-Eu, NaI-SrCl2-Eu, and NaI-BaI2-Eu compounds in the energy range of 3.7–18 eV at 10 and 295 K and investigate the phase formation in these crystalline systems. The NaI-SrI2(1 mol %)-Eu(0.02 mol %) crystalline system has revealed formation of SrI2 microcrystals activated with europium ions and dispersed in the NaI matrix. Formation of SrCl2-Eu2+ microcrystals dispersed in a NaI matrix is observed for NaI-SrCl2(1 mol %)-Eu(0.02 mol %) crystalline system. The mechanisms of aggregation of impurity ions and specific features of luminescence excitation for europium ions in dispersed microcrystals are discussed.

Study of the spectral-luminescence parameters of LuPO4-Ce nanoparticles upon the excitation by X-ray quanta and synchrotron radiation with photon energies of 4–25 eV was performed. Nanoparticles with mean size about a=35 nm and nanoparticles with size less than 12 nm reveal the different structures of cerium centers. Luminescence efficiency of LuPO4-Ce nanoparticles of a<12 nm size strongly decreases upon the excitation in the range of band-to-band transitions as well as in the case of X-ray excitation.