Luminescence Component Research Articles

Native Luminescence and Luminescence Lifetime of Cytochrome P450 3A4 within Endoplasmic Reticulum Biomimetic Nanodiscs

Cytochrome P450 plays an important role in the metabolism of drugs and xenobiotic molecules within the human body. Cytochrome P450 is a hemeprotein and has been shown to luminesce in detergent solubilized solutions and in lipid bilayer membranes. Discussed here is: (1) the spectroscopic nature of the luminescence, (2) the lifetimes of the distinct components of luminescence, and (3) how the luminescence changes upon ligand binding. These studies were done in solution in the presence of detergent and in a lipid bilayer contained within a nanodisc. The composition of the lipid nanodisc is chemically identical to the human endoplasmic reticulum (ER) and allows for detergent free insertion of P450 and its redox partners.

A novel Eu3+-doped phosphate glass for reddish orange emission: Preparation, structure and fluorescence properties

As an indispensable component of full-color luminescence, the development of reddish orange light emitting materials cannot be ignored. Here, we prepared a novel Eu3+-doped P2O5–SrO–BaO–ZnO glasses with distinctive fluorescence properties. The effects of Eu2O3 content on the structure and properties of glasses were studied, aiming to provide a key guidance for the preparation of reddish orange light emitting glass. The prepared glasses consisted predominantly of metaphosphate units along with minor contribution from pyrophosphate and orthophosphate units. Three intensity parameters (Ω2,4,6) were estimated by Judd-Ofelt theory, which followed the trend as Ω2 > Ω4 > Ω6. Particularly, the intensity of 5D0 →7F4 transition was much greater than that of 5D0→7F2 transition as the Eu2O3 content exceeded 0.50 mol.%. Under excitation by 397 nm xenon lamp, the fluorescence lifetimes of glasses that emit reddish orange light were 2.49, 2.52, 2.61, 2.54 and 2.48 ms with increase in Eu2O3 content. Considering the common experimental errors, there was no significant change in the fluorescence lifetimes. The distinctive fluorescence properties indicate that this novel glass has potential applications in display devices.

Рентгенолюминесценция тетраподов ZnO, выращенных в присутствии примеси Сu и Au в исходной шихте

The morphology and luminescent properties of ZnO tetrapod powders with Cu and Au impurities obtained by pyrolytic carbothermal synthesis were studied. The X-ray luminescence spectrum of the samples is dominated by a broad band in the range from 450 to 650 nm. A weak band-edge luminescence band with a maximum at 391 nm is also registered. Measurements of the decay kinetics showed the presence of both fast (~ 1 ns) and slow (~ 850 ns) luminescence components, where the fast one generally did not exceed 1% of the integrated intensity. It is shown that with the used doping method, the incorporation of Cu and Au impurities into the ZnO lattice does not occur. In this case, the presence of Cu with a concentration of up to 9% does not affect the morphology and luminescent properties of tetrapods, while Au has an effect even at a concentration close to 1%.

New Perspectives on Photosystem II Reaction Centres

We apply the differential optical spectroscopy techniques of circular polarisation of luminescence (CPL) and magnetic CPL (MCPL) to the study of isolated reaction centres (RCs) of photosystem II (PS II). The data and subsequent analysis provide insights into aspects of the RC chromophore site energies, exciton couplings, and heterogeneities. CPL measurements are able to identify weak luminescence associated with the unbound chlorophyll-a (Chl-a) present in the sample. The overall sign and magnitude of the CPL observed relates well to the circular dichroism (CD) of the sample. Both CD and CPL are reasonably consistent with modelling of the RC exciton structure. The MCPL observed for the free Chl-a luminescence component in the RC samples is also easily understandable, but the MCPL seen near 680nm at 1.8K is anomalous, appearing to have a narrow, strongly negative component. A negative sign is inconsistent with MCPL of (exciton coupled) Qy states of either Chl-a or pheophytin-a (Pheo-a). We propose that this anomaly may arise as a result of the luminescence from a transient excited state species created following photo-induced charge separation within the RC. A comparison of CD spectra and modelling of RC preparations having a different number of pigments suggests that the non-conservative nature of the CD spectra observed is associated with the ‘special pair’ pigments PD1 and PD2.

Luminescence properties of laser-induced silver clusters in borosilicate glass

This paper describes the luminescence properties of small silver clusters formed by laser treatment of silver-doped borosilicate glass. Using irradiation by a Nd:YAG nanosecond laser system operating at the fourth harmonic wavelength (266 nm), areas are formed in the glass samples that emit bright luminescence peaking at about 600 nm when excited by UV light in the spectral range 300–390 nm. The influence is presented and discussed of the glass composition and the laser processing parameters on the emission characteristics. It is further shown that the luminescent properties are affected by the fluence of the excitation source, namely, a complete quenching of the emission is achieved above a certain value. The luminescence of the irradiated areas is explained by the formation of Ag clusters due to irradiation-induced reduction of Ag ions and increased atom mobility resulting from the local heating. The limited stability of the luminescent areas upon UV radiation can be related to heat-induced cluster decomposition and re-oxidation. The results obtained provide a new insight in the optical properties of noble-metal nanostructures and could form the basis of fabrication of complex optical systems and luminescent component used in the study of, e.g., biological systems.

Textile-fiber-embedded multiluminescent devices: A new approach to soft display systems

In the recent remarkable advances in soft electronic systems, light-emitting functions play a prominent role. In particular, polymer composite systems with embedded luminescent particles have attracted considerable attention as a luminescent component owing to their flexibility and simple fabrication. However, most flexible composite-based electroluminescent (EL) devices have coplanar structures, requiring mechanically compliant electrodes with high transmittance, durability, and stable electrical conductivity. This is a limitation for systems designed for providing superior flexible characteristics without loss of luminescence. Here, we introduce a novel EL device architecture—a durable/flexible textile-fiber-embedded polydimethylsiloxane and zinc sulfide (PDMS + ZnS) composite, driven by an in-plane electric field, which eliminates the requirement for high transmittance. On applying an AC voltage, light is radially emitted from the ZnS particles surrounding the fibers, originating from the radially distributed electric/optical fields; the rolling and stretching flexibilities are maintained during this process. The device also exhibits strong EL intensities in a thick emitting layer—a parameter on which EL and mechanoluminescent (ML) intensities in coplanar structures are dependent. This is because the electric field is applied between in-plane fibers. Using this smart design, simultaneously high EL and ML intensities can be simply achieved by embedding fibers in strong ML-emitting PDMS + ZnS. We also present a patterned device controlled by different fiber embedding depths, utilizing the vertical and in-plane electric fields. This application may provide a basis for the development of emerging soft display systems that require high luminescence as well as flexibility in the light-emitting components.

Research on electro-triggered luminescent switching behaviors of film materials containing green luminescence Tb-polyoxometalate

In order to achieve the green fluorescent switching of film materials constructed by pure inorganic cluster with green luminescence, a pure inorganic polyoxometalate constituent [Tb4(H2O)6(β-GeW10O38)2]12− (TbGeW) was firstly chosen as the research object because it contains luminescent component Tb3+ and electrochromism component GeW together in a framework. Through the reasonable molecular design, three green luminescent composite films (PEI/TbGeW)42, (PEI/P2W18/PEI/TbGeW)42 and {(PEI/P2W18)3/PEI/TbGeW}42 were successfully fabricated by layer-by-layer (LBL) assembly method. The prepared composite films were characterized by a series of technologies including UV–vis spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Cyclic Voltammetry (CV) and luminescence spectroscopy. The fluorescent switching performance of these composite films was investigated by an in situ spectroelectrochemical system consisted by electrochemical workstation and fluorescence spectrophotometer. The investigated results indicated that the green fluorescent switching of film {(PEI/P2W18)3/PEI/TbGeW}42 was thoroughly realized by the control of electrochemistry.

Suppression of the slow component of BaF2 crystal luminescence with a thin multilayer filter

The fast component of the barium fluoride (BaF2) crystal luminescence with the emission peak at 220 nm allows those crystals to be employed in fast calorimeters operating in harsh radiation environment. However, the slow component with the emission peak at 330 nm and about 85% of the total emission light could create big problems when working at a high radiation rate. In this work we report results of tests of multilayer filters that can suppress luminescence in the range from 250 nm to 400 nm, which covers most of the BaF2 slow component luminescence. The filters are made by spraying layers of rare earth oxides on a quartz glass substrate. Filters typically comprise 200-220 layers. A few filters were prepared by spraying thin layers on quartz glass. The filters have a peak transmittance of about 70-80% in the range of 200-250 nm. Measurements of the light output of the BaF2 crystal with and without a filter between the crystal readout end and the PMT demonstrate substancial suppression of the slow component. To our knowledge, this kind of filters are produced and tested for the first time.

Study of Bi-directional detection for ascorbic acid and sodium nitrite based on Eu-containing luminescent polyoxometalate

Eu-containing polyoxometalate K13Eu(SiMoW10O39)2·28H2O (Eu-SiMoW) owns the stimu-chromic and photoluminescence properties. An ingenious test of ascorbic acid (AA) and sodium nitrite (NaNO2) was carried out based on the dual properties of Eu-SiMoW in solutions. First, the redox reaction of Eu-SiMoW and AA generated the blue reduced Eu-SiMoW, accompanied by fluorescence quenching; then the redox reaction of the reduced Eu-SiMoW and NaNO2 made Eu-SiMoW back to its original pale yellow state with red luminescence. Accordingly, the content of AA and NaNO2 could be measured by the reversible change of color and luminescence of Eu-SiMoW. This bi-directional detection method is first discovered and proven to be a simple and effective method for the detection of AA and NaNO2. The proposed method exhibited a linear response range (LRR) from 0.1 to 0.9 mmol L−1 with a limit of detection (LOD) of 0.53 µmol L−1 in UV–vis spectra and 4.67 µmol L−1 in luminescence spectra for AA as well as a LRR from 0.05 to 0.4 mmol L−1 with a LOD of 1.16 µmol L−1 in UV–vis spectra and 5.39 µmol L−1 in luminescence spectra for NaNO2. Moreover, the fluorescence switching of Eu-SiMoW could be realized by reacting with reductant and oxidant through the redox reaction. The detection mechanism is considered as a fluorescence resonance energy transfer process between discolor component SiMoW and luminescence component Eu in Eu-SiMoW.

Analysis of evolution of electron-radiation-induced defects in white-luminescent, carbonized, mesoporous silica nanocomposite using transmission electron microscopy/cathodoluminescence

We examined the evolution of electron-radiation-induced defects in a white-luminescent, carbonized, mesoporous silica nanocomposite using cathodoluminescence (CL) and electron energy-loss spectroscopy associated with scanning transmission electron microscopy, in order to elucidate the microscopic origins of light emissions in the visible spectral range. The effects of electron irradiation on CL were analyzed based on the differential equations for kinetics of irradiation defects. The nanometric honeycomb silica framework was found to play essentially no role in the electron-excited light emission processes, in contrast to the case for photon-excited processes. The broad and continuous visible emission band in CL consisted of several luminescence components, that have been assigned to optically active point defects such as oxygen-deficient centers, and surface nonbridging oxygen hole centers (NBOHCs) in silica glass.

Simultaneous measurement method of pressure and temperature using dual-layer PSP/TSP with lifetime-based method

Recently, the application field of the pressure measurement technique using pressure sensitive paint (PSP) has been expanding. However, the temperature dependence of PSP is a serious obstacle to accurate pressure measurement in low gauge pressure conditions because PSP is an absolute pressure sensor. Therefore, the temperature information of PSP is indispensably required for accurate pressure measurement, especially in low gauge pressure conditions. As a result, both temperature information and pressure information with a function of temperature are required simultaneously to use the PSP in low gauge pressure conditions. Dual-layer PSP/temperature sensitive paint (TSP) (DL-PTSP) is one solution, but simultaneous measurement of pressure and temperature requires two optical filters to separate the luminescence of PSP and TSP, resulting in complex equipment and additional error caused by parallax. To solve the problem, we introduce a lifetime-based method for DL-PTSP that allows simultaneous measurement of pressure and temperature. It is a method which separates each component of luminescence with different lifetimes. Firstly, the DL-PTSP developed in this study was optimized by reducing the luminescence intensity of the PSP with a longer lifetime while maintaining the luminescence intensity of the TSP with a shorter lifetime, considering the lifetime measurement method. Secondly, we have clarified the optimum time conditions of the monolayer TSP and the monolayer PSP by analysing their luminescence decay process, by controlling the irradiation delay of the light source relative to the camera shutter. Thirdly, the sensitivity of the DL-PTSP was examined using conditions optimized for mono-layer TSP and PSP. The luminescence decay of the TSP component shows sufficient temperature dependence, while the pressure dependence is very small. On the other hand, the dependence of the luminescence decay of the PSP component on the temperature and pressure is almost equal to that of the mono-layer PSP. The results confirm the feasibility of the simultaneous measurement of pressure and temperature using DL-PTSP.

Spectroscopy of divalent samarium in alkaline-earth fluorides

Optical spectra (absorption, luminescence, decay of emission, spectra with time resolution) of Sm2+ ions in alkaline-earth fluoride crystals (CaF2, SrF2, BaF2) in the wavelength range 120–900 nm at 7–300 K were studied. By additive coloration of about 60% of the original Sm3+ is converted to Sm2+.One component of the decay of the Sm2+ emission was observed in BaF2 crystals with a lifetime of 16 ms (a slow component) and in CaF2 crystals with a lifetime of 1.3 μs (fast component) at low temperature. In SrF2 crystals, two decay of luminescence components are found in the millisecond and nanosecond time range. The luminescence spectra of the slow and fast components in CaF2, SrF2, BaF2 are similar, which confirms their attribution to forbidden 4f-4f and allowed 5d-4f transitions, respectively. The results obtained made it possible to clarify the position of the excited levels of Sm2+ 4f(5D0) and 5d(eg) relative to the bottom of the conduction band of alkaline-earth fluorides.

Eco-friendly polydimethylsiloxane-based self-supporting film containing europium-polyoxometalate: A flexible luminescent material for white light generation

Lanthanide (Ln3+)-doped suitable matrices exhibit unique luminescent properties which are important for applications in optoelectronic devices. Most of the Ln3+-based luminescent materials are, however, prepared in powder form using suitable robust inorganic host matrices. These matrices, often, experience lack of flexibility which is important for many applications such as LEDs and wearable devices, among others. To address this aspect, we report the preparation of flexible and highly transparent luminescent membranes based on polydimethylsiloxane-hydroxyurethanes (PDMSUr) as the hybrid framework and Europium-polyoxometalate (Eu(PW11)2) complex as the luminescent component. The PDMSUr, besides acting as green, transparent and flexible matrix, is found to increase the emission decay lifetime (from 1.5 ms to 3.0 ms) when Eu(PW11)2 is incorporated in the hybrid matrix. Moreover, upon UV excitation, the matrix exhibits a broader emission around 450 nm which, together with the characteristic emission of Eu3+ ions, leads to the generation of white light.

The Effect of Aggregation of Impurity Nitrogen on Diamond X-Ray Luminescence

Two samplings of 65 diamond crystals divided by the intensity of a slow X-ray luminescence component are studied from the Arkhangel’skaya and Karpinskogo-1 pipes. IR and EPR spectroscopies revealed a relationship between the nitrogen A and P2 centers of the diamonds and the presence of a slow X-ray luminescence component. Its absence in most diamonds with high content of P1 (C) centers is explained by the low number of A and P2 centers.

THE EFFECT OF AGGREGATION OF NITROGEN IMPURITY IN THE DIAMOND X-RAY LUMINESCENCE

65 diamond crystals from pipes «Arkhangelskaya» and «Karpinskogo-1» was divided into two parts by the intensity of the slow component of x-ray luminescence, and investigated by methods of IR spectroscopy and ESR. The relationship between the content of nitrogen in the diamond centers A and P2 and the presence of the slow component of x-ray luminescence have been found. The absence of this component of greater part of the crystals with a high content centers P1 (C) explained by a small number of centres A and P2

ОСОБЕННОСТИ ПРЕДСТАВЛЕНИЯ ФЕНОМЕНА СВЕТА В ЯЗЫКЕ И МЕТОДИКА ВЫДЕЛЕНИЯ КОМПОНЕНТОВ КОНЦЕПТА «СВЕЧЕНИЕ» (НА ПРИМЕРЕ РУССКИХ И АНГЛИЙСКИХ ГЛАГОЛОВ)

The article provides the selective analysis of the Russian and English verbs of the lexico-semantic group luminescence. the research material includes the basic verbs representing the basic components of the concept luminescence. By analyzing the definitions of the mentioned verbs the author identifies their basic and optional components and concludes that the verbs “светить” and “shine” represent the components of the concept structure, but at the same time the components represent in their own way the different fragments of the concept luminescence.

Differentiation of black writing ink on paper using luminescence lifetime by time-resolved luminescence spectroscopy

The time-resolved luminescence spectra and the lifetimes of eighteen black writing inks were measured to differentiate pen ink on altered documents. The spectra and lifetimes depended on the samples. About half of the samples only exhibited short-lived luminescence components on the nanosecond time scale. On the other hand, the other samples exhibited short- and long-lived components on the microsecond time scale. The samples could be classified into fifteen groups based on the luminescence spectra and dynamics. Therefore, luminescence lifetime can be used for the differentiation of writing inks, and luminescence lifetime imaging can be applied for the examination of altered documents.

Intrinsic oxygen vacancies mediated multi-mechano-responsive piezoluminescence in undoped zinc calcium oxysulfide

Piezoluminescence has achieved enormous advancement in the field of stress sensors, and mechano-driven lightings and displays; however the existing piezoluminescent materials universally need the external dopants of lanthanide or transition metal ions to create efficient luminescence. Herein, we report a bright piezoluminescence in undoped piezoelectric semiconductor CaZnOS, which is multi-mechano-sensitive to ultrasonic vibration, friction, impact and compression. Our experimental and density functional theory computational investigations indicate that the intrinsic oxygen vacancies of VO2+, VO+ and VO0 act as luminescent centers and trap states in multi-colored components of luminescence. In addition to saving resources and protecting environment, our research is expected to open a door for design and development of self-piezoluminescent materials, thereby largely expanding our understanding of piezoluminescent mechanism and promoting further utilization of piezoluminescence.

Identification of yellow luminescence centers in Be-doped GaN through pressure-dependent studies

Effective acceptor doping of wide-band-gap semiconductors is still an outstanding problem. Beryllium has been suggested as a shallow acceptor in GaN, but despite sporadic announcements, Be-induced p-type doping has never been practically realized. Be-doped GaN possesses two luminescence bands; one at 3.38 eV and a second near 2.2 eV at an energy close to that of the parasitic yellow luminescence often found in undoped GaN crystals. We have performed high hydrostatic pressure studies of bulk, Be-doped gallium nitride crystals using the diamond anvil cell technique. We observed a splitting of the yellow luminescence line under hydrostatic pressure into two components, one which is strongly dependent on applied pressure and another whose pressure dependence is more modest. Together with hybrid functional calculations, we attribute the strongly-varying component to the beryllium–oxygen complex. The second component of the yellow luminescence possesses very similar pressure behavior to the yellow luminescence observed in undoped samples grown by the same method, behavior which we find consistent with the CN acceptor. At higher pressure, we observe the vanishing of yellow luminescence and a rapid increase in luminescence intensity of the UV line. We explain this as the pressure-induced transformation of the Be–O complex from a highly localized state with large lattice relaxation to a delocalized state with limited lattice relaxation.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of ∼10 photons per event complicates energy discrimination–a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm × 3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.