共查询到20条相似文献,搜索用时 31 毫秒
1.
Inorganic cesium lead halide perovskites have evoked wide popularity because of their excellent optoelectronic properties, high photoluminescence (PL) quantum yield (PLQY), and narrowband emission. Here, cesium lead bromide (CsPbBr3) quantum dots (QDs) were synthesized via the ligand-assisted re-precipitation method. Post-synthesis treatment of CsPbBr3 QDs using antimony tribromide improved the PL stability and optoelectronic properties of the QDs. In addition, the PLQY of the post-treated sample was enhanced to 91% via post-treatment, and the luminescence observed was maintained for 8 days. The post-synthesis treatment ensured defect passivation and improved the stability of CsPbBr3 perovskite QDs. High-resolution transmission electron microscopy revealed the presence of more ordered, uniform-sized CsPbBr3 QDs after post-synthesis treatment, and the uniformity of the sample improved as the day passed. The formation of a mixed crystal phase was observed from X-ray diffraction in both as-synthesized, as well as post-treated QDs samples with the possibility of a polycrystalline nature in the post-treated CsPbBr3 QDs as per the selected area electron diffraction pattern. The X-ray photoelectron spectroscopy spectra confirmed the presence of antimony and the possibility of defect passivation in the post-treated samples. These QDs can act as potential candidates in various optoelectronic applications such as photodetectors and light-emitting diodes due to their high PLQY and longer lifetime. 相似文献
2.
Yinan Xu Lixin Yu Kangliang Peng Yakun Deng Youjun Zhao Xiaoling Zeng Ying Yu 《Luminescence》2023,38(5):536-545
Lead halide perovskite quantum dots (QDs) with high fluorescence efficiency and high color purity have a broad application prospect in the field of backlight display, but poor stability has been a key factor limiting their commercialization. Herein, we successfully synthesized CsPbBr3 QDs-KIT-6 (CsPbBr3-K6) composite by using KIT-6 molecular sieve as the limited template with a simple high temperature solid-phase method. Further, the semi-protected CsPbBr3 QDs in KIT-6 frame will spontaneously hydrolyze when encountering water, and finally the double-encapsulated CsPbBr3 QDs-KIT-6@PbBr(OH) (CsPbBr3-K6@PbBr(OH)) composite are obtained. CsPbBr3-K6@PbBr(OH) composite shows excellent green emission properties, including a photoluminescence quantum yield (PLQY) (~73%) and a narrow emission linewidth of 25 nm. It is interesting that, the composite has excellent stability, including water stability without attenuation of fluorescence intensity after soaking in water for 60 days, thermal stability of 120°C heating–cooling cycle, and excellent optical stability without attenuation under continuous ultraviolet irradiation. 相似文献
3.
Europium‐activated rare earth fluoride (LnF3:Eu3+–Ln = La,Gd) nanocrystals prepared by using ionic liquid/NH4F as a fluorine source via hydrothermal synthesis
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lanthanide (Ln) fluorides are considered exceptional luminescent rigid host matrices for various optical active Ln3+ ions due to their high refractive index, high chemical stability and low phonon energy, leading to the low probability of non‐radiative decay, which results in higher photoluminescence quantum yield (PLQY) (usually higher than oxide hosts). In this study, Eu3+‐activated Ln fluorides (LnF3:Eu3+–Ln = La, Gd) are synthesized by the hydrothermal method using 1‐butyl‐3‐methylimidazolium tertrafluoroborate [BMIBF4] and NH4F as fluorine precursors. The synthesized nanocrystals (NCs) are structurally and morphologically characterized, and their optical properties investigated using spectrofluorometry. The X‐ray diffraction (XRD) patterns of Eu3+‐substituted and ‐unsubstituted LnF3 (prepared from a different fluorine source) are indexed based on the hexagonal and orthorhombic crystal structure, respectively. Average crystalline sizes are calculated using the Scherrer equation and it is found that the synthesized NCs have an average crystalline size of 12–35 nm. Transmission electron microscopy (TEM) images reveal that the NCs are well dispersed and nearly ellipsoid, with an average size of ~ 5 nm. Eu3+‐activated NCs show characteristic excitation and emission spectra. The emission spectra show both magnetic (5D0–7F1) and electric (5D0–7F2) dipole transition with appropriate CIE color coordinates; however, the intensity of the magnetic dipole transition is high, which is in accordance with local site symmetry. Owing to their unique size and excellent optical properties, the synthesized NCs may have potential application in the fields bio‐imaging and solar concentrators. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
4.
B. N. Swathi B. R. Radha Krushna B. Daruka Prasad S. C. Sharma Balanehru Subramanian H. Nagabhushana 《Luminescence》2023,38(3):232-249
Latent fingerprints (LFPs) are one among the most important types of evidences at crime scenes because of the distinctiveness and tenacity of the friction ridges in fingerprints (FPs). Therefore, it is essential in forensic science to develop a reliable method to detect LFPs. Traditional detection methods still face a number of difficulties, such as limited sensitivity, low contrast, strong background, and complex processing stages. In this study, MgO-ZrO2:Tb3+ (1–5 mol%) (MZ:Tb) nanocomposites (NCs) were prepared via a simple solution combustion (SC) method at low temperature. The photoluminescence (PL) investigation demonstrates that when excited at 379 nm, the produced NCs emits distinctive emission peaks of terbium ions (Tb3+). According to the photometric results, the NCs can be employed as warm light NCs and emit light in the green portion of the colour spectrum. The estimated optical band gap from diffuse reflectance spectra is found to be in the range 4.84–4.97 eV. Regardless of the type of surface being used, the optimized MgO-ZrO2:Tb3+ (4 mol%) (MZ:4Tb) NCs has a strong ability to minimize background fluorescence interference. With high contrast LFP and I–V type of cheiloscopy, these NCs present a flexible fluorescent mark for the identification of levels 1–3 details in forensic investigation. 相似文献
5.
Yaqian Zheng Yanyu Duan Yun Ye Xingke Zheng Aochen Du Enguo Chen Sheng Xu Tailiang Guo 《Luminescence》2024,39(2):e4691
The preparation of perovskite quantum dots (PQDs) using an in situ inkjet printing method is beneficial for improving the problems of aggregation and photoluminescence (PL) quenching during long-term storage. However, the stability of PQDs prepared using this method is still not ideal, and the morphology of in situ-printed patterns needs to be optimized. To address these problems, this study introduced polymethyl methacrylate (PMMA) into the process of in situ inkjet printing of PQDs and explored the effect of PMMA on the in situ patterning effect of PQDs. The results showed that using a mixed precursor solution containing a small amount of PMMA as the printing ink can slow down the shrinkage process of ink droplets and improve the uniformity of film formation. As the printing substrate, PMMA provided a suitable high-viscosity environment for the in situ growth of PQDs. This could effectively suppress the coffee ring effect. In addition, the interaction between the C=O=C group in PMMA and metal ion Pb2+ in the CsPbBr3 precursor molecules was favourable to enhancing the density of PQDs. The prepared PMMA-coated CsPbBr3 quantum dots (QDs) pattern had high stability and could maintain at 90.08% PL intensity after 1 week of exposure to air. 相似文献
6.
A new ion sensor based on hybrid SiO2‐coated CdTe nanocrystals (NCs) was prepared and applied for sensitive sensing of Cu2+ and Ag+ for the selective quenching of photoluminescence (PL) of NCs in the presence of ions. As shown by ion detection experiments conducted in pure water rather than buffer solution, PL responses of NCs were linearly proportional to concentrations of Cu2+ and Ag+ ions < 3 and 7 uM, respectively. Much lower detection limits of 42.37 nM for Cu2+ and 39.40 nM for Ag+ were also observed. In addition, the NC quenching mechanism was discussed in terms of the characterization of static and transient optical spectra. The transfer and trapping of photoinduced charges in NCs by surface energy levels of CuS and Ag2S clusters as well as surface defects generated by the exchange of Cu2+ and Ag+ ions with Cd2+ ion in NCs, resulted in PL quenching and other optical spectra changes, including steady‐state absorption and transient PL spectra. It is our hope that these results will be helpful in the future preparation of new ion sensors. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
Ashraf Yousefzadeh Jafar Abolhasani Javad Hassanzadeh Mohammad Hossein Somi 《Luminescence》2019,34(2):261-271
A novel and sensitive chemiluminescence (CL) procedure based on the synergetic catalytic effects of gold nanoclusters (Au NCs) and graphene quantum dots (GQDs) was developed for the reliable measurement of cimetidine (CM). The initial experiments showed that the KMnO4‐based oxidation of alkaline rhodamine B (RhoB) generated a very weak CL emission, which was intensively enhanced in the simultaneous presence of Au NCs and GQDs. CL intermediates can be adsorbed and gathered on the surface of Au NCs, becoming more stable. GQDs participate in the energy transferring processes and facilitate them. These improving effects were simultaneously obtained by adding both Au NCs and GQDs into the RhoB‐KMnO4 reaction. Consequently, the increasing effect of the Au NCs/GQDs mixture was more than that of pure Au NCs or GQDs, and a new nano‐assisted powerful CL system was achieved. Furthermore, a marked quenching in the emission of the introduced CL system was observed in the presence of CM, so the system was examined to design a sensitive sensor for CM. After optimization of influencing parameters, the linear lessening in CL emission intensity of KMnO4‐RhoB‐Au NCs/GQDs was verified for CM concentrations in the range 0.8–200 ng ml?1. The limit of detection (3Sb/m) was 0.3 ng ml?1. Despite being a simple CL method, good sensitivity was obtained for CM detection with reliable results for CM determination in human urine samples. 相似文献
8.
The purpose of this work was to optimize the process parameters required for the production of spray-dried oily core nanocapsules
(NCs) with targeted size and drug yield using a two-level four-factor fractional factorial experimental design (FFED). The
coded process parameters chosen were inlet temperature (X
1), feed flow rate (X
2), atomizing air flow (X
3), and aspiration rate (X
4). The produced NCs were characterized for size, yield, morphology, and powder flowability by dynamic light scattering, electron
microscope, Carr’s index, and Hausner ratio measurement, respectively. The mean size of produced NCs ranged from 129.5 to
444.8 nm, with yield varying from 14.1% to 31.1%. The statistical analysis indicated an adequate model fit in predicting the
effect of process parameters affecting yield. Predicted condition for maximum yield was: inlet temperature 140°C, atomizing
air flow 600 L/h, feed flow rate 0.18 L/h, and aspiration air flow set at 100%, which led to a yield of 30.8%. The morphological
analysis showed the existence of oily core and spherical nanostructure. The results from powder flowability analysis indicated
average Carr’s index and Hausner ratio of 42.77% and 1.76, respectively. Spray-dried oily core NCs with size lower than 200 nm
were successfully produced, and the FFED proved to be an effective approach in predicting the production of spray-dried NCs
of targeted yield. 相似文献
9.
Photoluminescence,cathodoluminescence and thermal stability of Sm3+‐activated Sr3La(VO4)3 red‐emitting phosphors
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A series of Sm3+‐activated Sr3La(VO4)3 phosphors were synthesized by a facile sol‐gel method. X‐ray diffraction patterns and photoluminescence (PL)/cathodoluminescence (CL) spectra as well as PL decay curves were employed to characterize the obtained samples. Upon 402 nm light excitation, the characteristic emissions of Sm3+ ions corresponding to 4G5/2→6HJ transitions were observed in all the as‐prepared products. The PL emission intensity was increased with increase in Sm3+ ion concentration, while concentration quenching occurred when the doping concentration was over 4 mol%. The non‐radiative energy transfer mechanism for concentration quenching of Sm3+ ions was dominated by dipole–dipole interaction and the critical distance was around 21.59 Å. Furthermore, temperature‐dependent PL emission spectra revealed that the obtained phosphors possessed good thermal stability with an activation energy of 0.19 eV. In addition, the CL spectra of the samples were almost the same as the PL spectra, and the CL emission intensity showed a tendency to increase with increase in accelerating voltage and filament current. These results suggest that the Sm3+‐activated Sr3La(VO4)3 phosphors with good color coordinates, high color purity and superior thermal stability may be a potential candidate for applications in white light‐emitting diodes and field‐emission displays as red‐emitting phosphors. 相似文献
10.
Uniform Pomegranate‐Like Nanoclusters Organized by Ultrafine Transition Metal Oxide@Nitrogen‐Doped Carbon Subunits with Enhanced Lithium Storage Properties
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bingqiu Liu Qi Zhang Zhanshuang Jin Lingyu Zhang Lu Li Zhigang Gao Chungang Wang Haiming Xie Zhongmin Su 《Liver Transplantation》2018,8(7)
Uniform pomegranate‐like nanoclusters (NCs) organized by ultrafine transition metal oxide@nitrogen‐doped carbon (TMO@N–C) subunits (diameter ≈ 4 nm) are prepared on a large scale for the first time through a facile, novel, and one‐pot approach. Taking pomegranate‐like Fe3O4@N–C NCs as an example, this unique structure provides short Li+/electron diffusion pathways for electrochemical reactions, structural stability during cycling, and high electrical conductivity, leading to superior electrochemical performance. The resulting pomegranate‐like Fe3O4@N–C NCs possess a high specific capacity (1204.3 mA h g?1 at 0.5 A g?1 over 100 cycles), a stable cycle life (1063.0 mA h g?1 at 1 A g?1, 98.4% retention after 1000 cycles), and excellent rate capacities (606.0 mA h g?1 at 10 A g?1, 92.0% retention; 417.1 mA h g?1 at 20 A g?1, 91.7% retention after 1000 cycles). 相似文献
11.
Camila M.B. Leite Silva Airton G. Bispo‐Jr Felipe S.M. Canisares Shirley A. Castilho Sergio A.M. Lima Ana M. Pires 《Luminescence》2019,34(8):877-886
Eu3+–β‐diketonate complexes are used, for example, in solid‐state lighting (SSL) or light‐converting molecular devices. However, their low emission quantum efficiency due to water molecules coordinated to Eu3+ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu3+ tetrakis complexes based on [Q][Eu(tfaa)4] and [Q][Eu(dbm)4] (Q1 = C26H56N+, Q2 = C19H42N+, and Q3 = C17H38N+), replacing the water molecules in the tris stoichiometry. The tetrakis β‐diketonates showed desirable thermal stability for SSL and, under excitation at 390 nm, they displayed the characteristic Eu3+ emission in the red spectral region. The quantum efficiencies of the dbm complexes achieved values as high as 51%, while the tfaa complexes exhibited lower quantum efficiencies (28–33%), but which were superior to those reported for the tris complexes. The structures were evaluated using the Sparkle/PM7 model and comparing the theoretical and the experimental Judd–Ofelt parameters. [Q1][Eu(dbm)4] was used to coat a near‐UV light‐emitting diode (LED), producing a red‐emitting LED prototype that featured the characteristic emission spectrum of [Q1][Eu(dbm)4]. The emission intensity of this prototype decreased only 7% after 30 h, confirming its high photostability, which is a notable result considering Eu3+ complexes, making it a potential candidate for SSL. 相似文献
12.
Yufeng Yuan Kehan Huang Mengfang Chang Cuifang Qin Sanjun Zhang Haifeng Pan Yan Chen Jianhua Xu 《Analytical biochemistry》2016
Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD+ (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD+ concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD+ and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD+ levels from 100 to 4000 μM, as well as label NAD+/NADH (reduced form of NAD) ratios in the range of 1–50. 相似文献
13.
Crystal structure and luminescence properties of the blue‐green‐emitting Ba9(Lu,Y)2Si6O24:Ce3+ phosphor
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Huawei Xu Zhi Zhou Yongfu Liu Qunxing Liu Zhiyuan He Shen Wang Linyi Huang Hongbo Zhu 《Luminescence》2017,32(5):812-816
Samples of the Ba9(Lu2‐xYx)Si6O24:Ce3+ (x = 0–2) blue‐green phosphors were synthesized by solid‐state reactions. All the samples exhibited a rhombohedral crystal structure. As the Y3+ concentration increased, the diffraction peaks shifted to the small angle region and the lattice parameters increased due to the larger ionic radius of Y3+ (r = 0.900 Å) compared with that of Lu3+ (r = 0.861 Å). Under 400 nm excitation, samples exhibited strong blue‐green emissions around 490 nm. The emission bands had a slight blue shift that resulted from weak crystal‐field splitting with increasing Y3+ concentration. Luminescence intensity and quantum efficiency (QE) decreased with increasing Y3+ concentration. The internal QE decreased from 74 to 50% and the external QE decreased from 50 to 34% as x increased from 0 to 2. The thermal stability of the Lu series was better than that of the Y‐series. The excitation band peak around 400 nm matched well with the emission light from the efficient near‐ultraviolet (NUV) chip. These results indicate promising applications for these NUV‐based white light‐emitting diodes. 相似文献
14.
Eu3+‐doped polystyrene and polyvinylidene fluoride nanofibers made by electrospinning for photoluminescent fabric designing
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sangeeta Gopichandra Itankar Manjusha Prafulla Dandekar Subhash Baburao Kondawar Bhaskar Marotrao Bahirwar 《Luminescence》2017,32(8):1535-1540
Eu3+‐doped polystyrene and polyvinylidene fluoride (PVDF/Eu3+ and PS/Eu3+) nanofibers were made using electrospinning. These fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR), energy dispersive spectroscopy (EDX) and photoluminescence (PL). Spectral analysis of PVDF/Eu3+ and PS/Eu3+ nanofibers was based on their emission spectra. A bright red emission was noticed from Eu3+ that was assigned to the hypersensitive 5D0 → 7F2 transition. The enhanced intensity ratios of 5D0 → 7F2 to 5D0 → 7F1 transitions in the nanofibers indicated a more polarized chemical environment for the Eu3+ ions and greater hypersensitivity for the 5D0 → 7F2 transition, which showed the potential for application in various polymer optoelectronic devices. The Eu3+‐doped polymer (PVDF/Eu3+ and PS/Eu3+) nanofibers are suitable for the photoluminescent white light fabric design of smart textiles. This paper focuses on the potential application of smart fabrics to address challenges in human life. 相似文献
15.
Synthesis and characterization of pure and Li+ activated Alq3 complexes for green and blue organic light emitting diodes and display devices
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pure and Li+‐doped Alq3 complexes were synthesized by simple precipitation method at room temperature, maintaining the stoichiometric ratio. These complexes were characterized by X‐ray diffraction, ultraviolet‐visible absorption and Fourier transform infrared and photoluminescence (PL) spectra. X‐ray diffraction analysis reveals the crystalline nature of the synthesized complexes, while Fourier transform infrared spectroscopy confirm the molecular structure, the completion of quinoline ring formation and presence of quinoline structure in the metal complex. Ultraviolet‐visible and PL spectra revealed that Li+ activated Alq3 complexes exhibit the highest intensity in comparison to pure Alq3 phosphor. Thus, Li+ enhances PL emission intensity when doped into Alq3 phosphor. The excitation spectra lie in the range of 383–456 nm. All the synthesized complexes other than Liq give green emission, while Liq gives blue emission with enhanced intensity. Thus, he synthesized phosphors are the best suitable candidates for green‐ and blue‐emitting organic light emitting diode, PL liquid‐crystal display and solid‐state lighting applications. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
16.
《Harmful algae》2014
Benthic dinoflagellates of the genus Ostreopsis are found all over the world in temperate, subtropical, and tropical coastal regions. Our recent studies revealed that a putative “cryptic” species of Ostreopsis ovata is present widely along Japanese coasts. This organism, Ostreopsis sp. 1, possesses palytoxin analogs and thus its toxic blooms may be responsible for potential toxification of marine organisms. To evaluate the bloom dynamics of Ostreopsis sp. 1, the present study examined the growth responses of Ostreopsis sp. 1 strain s0716 to various light intensities (photon flux densities: μmol photons m−2 s−1) using a newly devised photoirradiation-culture system. This novel system has white light-emitting diodes (LEDs) capable of more closely simulating the wavelength spectrum of light entering the oceanic water column than do fluorescent tubes and halogen lamps. In this system, the light intensity of the white LEDs was reduced through two polarizing filters by varying the rotation angles of the filters. Thereby, the new system was capable of culturing microalgae under well-controlled light intensity conditions. Ostreopsis sp. 1 grew proportionally when light intensity was increased from 49.5 to 199 μmol photons m−2 s−1, but its growth appeared to be inhibited slightly at ≥263 μmol photons m−2 s−1. The relationship between observed growth rates and light intensity was calculated at R > 0.99 (P < 0.01) using a regression analysis with a modified equation of the photosynthesis-light intensity (P-L) model. The equation determined the critical light intensities for growth of Ostreopsis sp. 1 and the organism's growth potential as follows: (1) the threshold light intensity for growth: 29.8 μmol photons m−2 s−1; (2) the optimum light intensity (Lm) giving the maximum growth rate (μmax = 0.659 divisions day−1): 196 μmol photons m−2 s−1; (3) the optimum light intensity range (Lopt) giving ≥95% μmax: 130–330 μmol photons m−2 s−1; (4) the semi-optimum range (Lsopt) giving ≥80% μmax: 90 to over 460 μmol photons m−2 s−1. The Lsopt represents 4.5–23% ambient light intensity present in surface waters off of a temperate region of the Japanese coast, Tosa Bay; putatively, this semi-optimum range of light intensity appears at depth of 12.9–27.8 m. Considering these issues, our data indicate that Ostreopsis sp. 1 in coastal environments may form blooms at ca. ∼28 m depth in regions along Japanese coasts. 相似文献
17.
Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+,Dy3+ co‐doped Ba2MgSi2O7 phosphors
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+‐doped and Eu2+,Dy3+‐co‐doped Ba2MgSi2O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid‐state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and energy‐dispersive X‐ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2MgSi2O7:Eu2+ showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2MgSi2O7:Eu2+Dy3+ showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+. TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu2+ doping in Ba2MgSi2O7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co‐doped in Ba2MgSi2O7:Eu2+ and maximum TL intensity was observed for 2 mol% of Dy3+. TL emission spectra of Ba1.95MgSi2O7:0.05Eu2+ and Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co‐doping. The trap depths were calculated to be 0.54 eV for Ba1.95MgSi2O7:0.05Eu2+ and 0.54 eV and 0.75 eV for Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors. It was observed that co‐doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2MgSi2O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1', '4f7' has been corrected to '4f7', 'Ba1.95' has been corrected to 'Ba1.95' and 'Ba1.93' has been corrected to 'Ba1.93' respectively.] 相似文献
18.
Chunlei Ma Wensheng Ren Jianke Tang Xiaoli Wang Dongxin Ji Rongqian Meng Cuihong Zhang Qi Wang 《Luminescence》2019,34(7):767-773
Taking advantage of the compelling properties of d ‐penicillamine (d ‐PA) combined with copper, a method for the sensitive and selective determination of d ‐PA was established using copper nanocluster (Cu NC)‐based fluorescence enhancement. d ‐PA molecules containing a thiol compound showed a strong tendency to combine with the surface of Cu NCs, causing the re‐dispersion of nanoclusters and therefore fluorescence intensity was enhanced. Fluorescence enhancement efficiency of Cu NCs induced by d ‐PA was linear, with the d ‐PA concentration varying from 0.6–30 μg ml?1 (R2 = 0.9952) and with a detection limit of 0.54 μg ml?1. d ‐PA content in human urine samples was detected with recoveries of 104.8–112.99%. Fluorescence‐enhanced determination of d ‐PA using Cu NCs was established for the first time and this rapid, easy and sensitive method should attract much attention for this application. 相似文献
19.
Ranjana Singh Prabhat Kumar Srivastava Vijay Pratap Singh Gunjan Dubey Sheo Mohan Prasad 《Acta Physiologiae Plantarum》2012,34(3):1119-1131
The extent of mercury (Hg) toxicity in the heterocystous cyanobacterium Nostoc muscorum grown for 72 h in three different light intensities was tested for various physiological parameters viz. growth, pigment contents, photosynthesis, respiration, reactive oxygen species (ROS), malondialdehyde formation and antioxidants.
A general reduction in growth and pigments, whole cell O2-evolution, photosynthetic electron transport activities and 14CO2-fixation was observed in a metal concentration–dependent manner, and this effect was more pronounced in high light (130 μmol
photon m−2 s−1)–exposed cells as compared to low (10 μmol photon m−2 s−1) and normal (70 μmol photon m−2 s−1) light intensity–exposed cells; however, carotenoids and respiration showed reverse trend. Among photosynthetic electron
transport activities, whole chain activity was found to be most sensitive in comparison with photosystem II (PS II) and photosystem
I (PS I). Comparing the different photosynthetic processes, 14CO2-fixation was most affected in cyanobacterial cells when exposed to Hg and different light intensities. After application
of various exogenous electron donors, diphenyl carbazide was found to be more effective to restore PS II activity, suggesting
that site of damage lies in between oxygen evolving complex and PS II. Level of oxidative stress (superoxide radical and lipid
peroxidation) was maximum at 3.0 μM of Hg when coupled with high light intensity (except hydrogen peroxide). A dose-dependent
increase in enzymatic antioxidants such as superoxide dismutase, peroxidase and catalase as well as non-enzymatic antioxidants
such as proline, ascorbate, cysteine (except under high light intensity) and non-protein thiols [NP-SH] was observed, which
further increased with the increase in light intensity. It was noticed that Hg intoxicates N. muscorum through ROS production, which is aggravated along with the increase in light intensity. Overall results suggest that the
severity of the metal stress does increase with Hg concentrations but when coupled with light, it was the light intensity
that determines the extent of Hg toxicity. 相似文献
20.
Photoluminescence (PL) and thermoluminescence (TL) properties of rare earth (RE) ion (RE = Dy3+, Sm3+, Ce3+, Tb3+) activated microcrystalline BaMgP2O7 phosphors are presented in this work. Non‐doped and doped samples of BaMgP2O7 were prepared using a solid state diffusion method and characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), PL and TL. The XRD measurement confirmed the phase purity of the BaMgP2O7 host matrix. The average particle size was found through SEM measurement to be around 2 μm. All activators using the PL technique displayed characteristic excitation and emission spectra that corresponded to their typical f → f and f → d transitions respectively. Thermoluminescence measurements showed that BaMgP2O7:RE (RE = Dy3+, Sm3+, Tb3+, Ce3+) and co‐doped BaMgP2O7:Ce3+,Tb3+ phosphors have also TL behaviour. 相似文献