Re(I) Complexes as Backbone Substituents and Cross-Linking Agents for Hybrid Luminescent Polysiloxanes and Silicone Rubbers

This study focuses on the synthesis of hybrid luminescent polysiloxanes and silicone rubbers grafted by organometallic rhenium(I) complexes using Cu(I)-catalyzed azido-alkyne cycloaddition (CuAAC). The design of the rhenium(I) complexes includes using a diimine ligand to create an MLCT luminescent center and the introduction of a triple C≡C bond on the periphery of the ligand environment to provide click-reaction capability. Poly(3-azidopropylmethylsiloxane-co-dimethylsiloxane) (N3-PDMS) was synthesized for incorporation of azide function in polysiloxane chain. [Re(CO)3(MeCN)(5-(4-ethynylphenyl)-2,2′-bipyridine)]OTf (Re1) luminescent complex was used to prepare a luminescent copolymer with N3-PDMS (Re1-PDMS), while [Re(CO)3Cl(5,5′-diethynyl-2,2′-bipyridine)] (Re2) was used as a luminescent cross-linking agent of N3-PDMS to obtain luminescent silicone rubber (Re2-PDMS). The examination of photophysical properties of the hybrid polymer materials obtained show that emission profile of Re(I) moiety remains unchanged and metallocenter allows to control the creation of polysiloxane-based materials with specified properties.

A Feasible and Facile Method for the Anticounterfeiting of Down Fiber

In order to prevent counterfeiting of down fiber from consumers, rare earth fluorescent materials are developed in the field of material identification and anticounterfeiting. Herein, the development of verifiable down fiber based on infrared excitation-infrared emission was described. A novel method was approached to prepare security down fiber, which involved modification of down-conversion nanoparticles (DCNPs) by sulfonic groups and self-assembly onto down fiber through electrostatic force. DCNPs were successfully prepared from ytterbium-deposited NaYF4 nanoparticles using a complexation precipitation approach, in which the trivalent ytterbium ions served as the luminescent center. Sulfonic down-conversion nanoparticles (SO3-SiO2@DCNPs) were fabricated by the hydrolysis of 3-mercaptopropyl triethoxysilane (MPTES) and next oxidation to enhance the combination of the DCNPs with down fiber. The synthesis of DCNPs and SO3-SiO2@DCNPs and its pendant to down were confirmed by XRD, SEM, XPS, FT-IR, Zeta potential meter, and PL, which revealed the presence of DCNPs in the size average 86 nm. The obtained DCNPs and security down fiber were launching an invisible red-shifted emission of 930∼1080 nm (corresponding to the 2F5/2 ⟶ 2F7/2 transitions in Yb3+). After washing, the infrared emission of security down fiber was evaluated and proved to be effective with fine results, which showed its potential application in the field of security.

Stacked nanocarbon photosensitizer for efficient blue light excited Eu(III) emission

Photosensitizer design to allow effective use of low-energy light is important for developing photofunctional materials. Herein, we describe a rational photosensitizer design for effective use of low-energy light. The developed photosensitizer is a stacked nanocarbon based on a rigid polyaromatic framework, which allows efficient energy transfer from the low-energy T1 level to the energy acceptor. We prepared an Eu(III) complex consisting of a luminescent center (Eu(III)) and stacked-coronene photosensitizer. The brightness of photosensitized Eu(III) excited using low-energy light (450 nm) is more than five times higher than the maximum brightness of previously reported Eu(III) complexes.

Rare earth ion Tb3+ doped natural sodium feldspar (NaAlSi3O8) Luminescent properties and energy transfer

In this study, Tb3+—doped natural sodium feldspar (NaAlSi3O8) phosphors have been successfully prepared using high−temperature solid—state method with natural sodium feldspar as a substrate. Energy—dispersive X—ray spectrometry analysis (EDX) of NaAlSi3O8 showed that 0.03 wt% of Eu element was present, and elemental distribution mapping analysis showed that the distribution of trace Eu in minerals was aggregated. The crystal structure and luminescence properties of the natural sodium Eu—containing feldspar and synthetic sodium feldspar NaAlSi3O8:Eu3+, Tb3+ phosphors are discussed in detail. The crystal structure analysis of the samples showed that the Na+ in the natural matrix was partly replaced by the doped Tb3+. Studies on the photoluminescence properties of the samples indicate that Eu does not form a luminescent center in the natural mineral, however, the strong characteristic peak of Eu3+ at 615 nm appears after doping with Tb3+ and the peak at 615 nm increases with the increase of Tb3+ concentration. According to the above spectral results, the energy transfer from Tb3+ to Eu3+ is obtained. Through the measurement and analysis of color coordinates, it is found that with the increase of Tb3+ concentration, the luminescence color of the samples can be regulated in the green to red region. NaAlSi3O8:Eu3+ Tb3+ phosphors has potential application value.

Люминесцентные и нелинейно-оптические свойства боратов LnGa-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=- (Ln = Nd, Sm, Tb, Er, Dy, Ho)

Luminescence spectra of single crystals of rare-earth gallium borates LnGa_3(BO_3)_4 (Ln = Nd, Sm, Tb, Er, Dy, or Ho) at room (300 K) and cryogenic (10 K) temperatures are presented for the first time. Photoluminescence has been recorded in the wavelength range of 470–5000 nm (2000–21 300 cm^–1) with a high spectral resolution (down to 0.1 cm^–1) upon excitation by different diode lasers. The spectra obtained cannot be unambiguously interpreted within one luminescent center, which can be due to the presence of defects and/or inclusions of other crystalline phases. The optical nonlinearity of rare-earth–gallium borates has been estimated using the Kurtz–Perry powder technique. The typical intensities of the second-harmonic generation in gallium borate powders are 30–40 (with respect to quartz), and the optical nonlinearity is as good as the nonlinearity of the efficient rare-earth aluminum borate YAl_3(BO_3)_4.

The Spectra of X-ray and Photoluminescence of High-Resistance Crystals of ZnSe

The luminescence spectra of high-resistance ZnSe crystals consist of two main bands with maxima at 630 nm (1.92 eV) and 970 nm (1.28 eV). The planned comparison has been carried out between the spectra of X-ray luminescence and photoluminescence of ZnSe among themselves in the spectral region from 400 to 1200 nm at different excitation intensities and different temperatures (8, 85, 295, and 420 K). It is found that the forms of luminescence bands do not depend on the excitation intensities. The band form with a maximum at 970 nm also does not depend on the excitation type, and the band at 630 nm differs slightly under the X-ray and UV excitations. The temperature dependences of the spectral positions of bands’ maxima and their half-widths are analyzed. A conclusion is drawn that the 970-nm emission band is elementary. A short-wavelength shift of the spectral maximum of the 630-nm band with increasing the temperature makes it possible to conclude that this luminescence band is non-elementary. This correlates with the previously discovered feature of this band related to the realization of two recombination mechanisms (electron and hole) at this luminescent center.

Evaluation of Radio-Photoluminescence Spectra of Copper-Doped Phosphate Glass Dosimeter Irradiated with Ionized Particles

A radio-photoluminescence (RPL) dosimeter with a copper-ion luminescent center was fabricated to evaluate its response in ionized particle detection. A focused proton microbeam with varying energies up to 3 MeV and heavy ions of 490 MeV osmium (Os) were employed along with X-rays to evaluate its performance in micrometer-scale radiation monitoring. The response to ionized particles was evaluated under focused proton beam irradiation where the peak wavelength differed from that obtained under X-ray irradiation. Two peaks were observed under Os irradiation where the secondary-generated particles and photons have a significant effect on the dosimeter. The results suggest that the fabricated RPL dosimeter with copper luminescence center could be used to estimate the irradiation effect of primary ionized particles separately from the effects of secondary particles, photons, and environmental background radiation.

Luminescence behaviour of Mn4+ions in seven coordination environments of K3ZrF7

A single-phased K3ZrF7:Mn4+has been successfully synthesized, in which Mn4+playing as the luminescent center to absorb blue light and emit red light. Obvious warm white light can be observed from the WLED based on this red phosphor.