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Smartphone-based three-channel ratiometric fluorescent device and application in filed analysis of Hg2+, Fe3+ and Cu2+ in water samples
摘要： Determination of metal ions in water samples, especially harmful heavy metal like mercury or essential elements like iron and copper, is an important work in environmental monitoring. Herein, we report a smartphone-based three-channel ratiometric fluorescence device for simultaneous determination of Hg2+, Fe3+ and Cu2+ in environmental samples on site. It was based on the fluorescence quench mechanism of Hg2+, Fe3+ and Cu2+ to three kinds of doped carbon quantum dots, which were prepared by pyrolysis methods using ammonium citrate, citric acid + 1,10-phenanthroline, and EDTA + thiourea as initial materials, respectively. By using a multivariate calibration method, the mutual interference among Hg2+, Fe3+ and Cu2+ can be corrected. Under the optimized conditions, the limits of detection for Hg2+, Cu2+ and Fe3+ are 3, 0.5, and 30 nM, respectively. The proposed device offers the advantage of portability, sensitivity and reliability for field analysis.
关键词： Smartphone,Heavy ions,Portable device,Carbon quantum dots,Ratiometric fluorescence,Triple-channel
更新于2025-09-11 14:15:04
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Waveguide laser potency of samarium doped BaSO4-TeO2-B2O3 glasses: Evaluation of structural and optical qualities
摘要： A series of samarium ions (Sm3+) doped barium-sulfur-telluro-borate glasses of composition (70-x)B2O3-15BaSO4-15TeO2-xSm2O3 (x ranged from 0.0 to 2.5 mol%) was prepared by melt-quenching method and examined via diverse analytical tools. Influence of changing Sm3+ doping contents on the structures and optical attributes of the proposed glasses was determined. The XRD pattern of as-quenched samples verified their glassy states. The FTIR spectra displayed the vibrational modes of tellurites and borates functional groups in the corresponding range of 460–850 cm?1 and 700–1650 cm?1. The EDX elemental maps confirmed the homogeneous distribution of the traced elements in the glass matrix. The UV–Vis–NIR absorption spectra of glasses exhibited nine distinct bands compatible with the transition from lower 6H5/2 state to the excited 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 states of Sm3+. The photoluminescence spectra showed four emission bands allotted to magnetic dipole 4G5/2 → 6H5/2 (moderate green at 562 nm), electric dipole dominated 4G5/2 → 6H7/2 (intense orange at 598 nm), electric dipole 4G5/2 → 6H9/2 (moderate red at 645 nm) and 4G5/2 → 6H11/2 (weak red at 703 nm) transitions in Sm3+, respectively. Glasses containing Sm2O3 contents above 1.0 mol % disclosed luminescence intensity quenching. Evaluated Judd-Ofelt intensity parameters Ω2, Ω4, and Ω6 were discerned from 1.48 × 10?20–4.2 × 10?20 cm2, 2.31 × 10?20–4.31 × 10?20 cm2 and 1.26 × 10?20–1.99 × 10?20 cm2 respectively. Furthermore, the lifetime of the samples decreases with increase in Sm3+ contents as unraveled by decay curve analysis. The achieved excellent spectroscopic properties of the proposed glass composition suggested their effectiveness as visible laser for waveguide applications.
关键词： Borate glasses,Samarium ions,Waveguide laser,Bonding parameter,Radiative properties
更新于2025-09-11 14:15:04
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Controlling energy distribution of fast ions and X-ray emission via target reliefs in ultrafast and relativistic laser plasma interaction
摘要： Secondary emission from laser produced plasma is governed by the electron distribution function. Therefore, its control is of utmost importance to steer the emission, e.g., of ultrashort bursts of high energy photons and ions for decisive application. Maximum gain is achieved if the laser light absorption by plasma is also maximized. In our theoretical analysis including comparison to recent experiments, we follow this route and study how the energy is transferred from a short laser pulse to the energy of fast ions and X-rays. We make use of ion and K-a emissions, which respond differently to branches of the electron distribution function when we optimize the laser light absorption via structuring of the target surface. Our investigation comprises laser intensities up to 5 (cid:2) 1020 W/cm2 produced with femtosecond near infrared laser pulses and titanium foil targets of a few micrometer thicknesses. In particular, we reveal an energy relaxation process of hot electrons, which determines the observed laser intensity dependence of secondary emission and points to the bene?t of target surface structuring in different optimization scenarios.
关键词： laser plasma,ultrafast laser,fast ions,electron distribution function,target reliefs,relativistic laser plasma interaction,X-ray emission
更新于2025-09-11 14:15:04
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Improving and Stabilizing Perovskite Solar Cells with Incorporation of Graphene in the Spiro-OMeTAD Layer: Suppressed Li Ions Migration and Improved Charge Extraction
摘要： Perovskite solar cells (PSCs) have achieved a huge success in power conversion efficiency (PCE), while they still suffer from the long-term stability problem caused by the intrinsic sensitivity of perovskites to moisture. 2,2’,7,7’-tetrakis (N, N-di-p-methoxyphenylamine) 9,9’-spirobifluorene (Spiro-OMeTAD) is widely used as the hole transport layer (HTL) in typical PSCs; meanwhile bis(trifuoromethane)sulfonimide lithium salt (Li-TFSI) proves its necessity as an additive in the Spiro-OMeTAD HTL to improve the hole mobility. However, the Li+ ions bring in high hygroscopicity and water-uptake effect that both aggravate degradation of the Spiro-OMeTAD HTL and thereby of the perovskite layers. Here, we modify the Li-TFSI-based Spiro-OMeTAD HTL by adding reduced graphene oxide (rGO). We verify that rGO provides adsorption sites for Li+ ions and subsequently suppresses Li+ migration. The water-uptake effect originated from Li+ ions is thus relieved and detestable pinholes in HTL caused by Li+ ion migration are eliminated. Consequently, the rGO-incorporated HTL remarkably improves the device stability that maintains the initial PCEs within 3% loss after 700 h under 40% humidity; whereas the pristine devices almost lose the efficiency after 620 h. In addition, the good conductivity of the rGO favors hole transport in the Spiro-OMeTAD, resulting in a promotion in PCEs from 17.7% to 19.3% by incorporating rGO in HTL. Our work takes an insight into the function of rGO in the HTL and demonstrates an effective way of improving the efficiency and stability of PSCs simultaneously.
关键词： Perovskite solar cells,lithium ions,moisture stability,reduced graphene oxide (rGO),charge extraction,ion migration
更新于2025-09-11 14:15:04
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Investigation of photo-induced electron transfer between amino-functionalized graphene quantum dots and selenium nanoparticle and it's application for sensitive fluorescent detection of copper ions
摘要： Copper ions play an essential role in some biological processes. Currently, there is a need for the development of convenient and reliable analytical methods for the Cu2+ measurement. In the present work, a sensitive fluorescence method was developed for the determination of copper ions. Amino-functionalized graphene quantum dots (af-GQDs) and selenium nanoparticles (Se NPs) were synthetized, respectively, and they were characterized via transmission electron microscope, infrared spectrum analysis and X-ray photoelectron spectrum measurement. Photo-induced electron transfer (PET) between the prepared two nanomaterials could effectively quench the fluorescence of af-GQDs. Cu(II) was reduced to Cu(I) in the presence ascorbic acid and Cu2Se was finally generated on Se NPs surface, which led to the declined PET efficiency and inhibited the fluorescence quenching of af-GQDs. The change in fluorescence intensity was linearly correlated to the logarithm of the Cu2+ concentration from 1 nM to 10 μM, with a detection limit of 0.4 nM under the optimal conditions. The detections of copper ions in water samples were realized via standard addition method and the recovery values varied from 98.7% to 103%. The proposed fluorescence method was also employed to analyze the uptake of Cu2+ into human cervical carcinoma HeLa cells and cisplatin-resistant HeLa cells (HeLa/DDP cells). The experimental results indicate that the decreased hCTR1 expression level in HeLa/DDP cells weakened the uptake of copper ions into these drug-resistant tumor cells.
关键词： photo-induced electron transfer,selenium nanoparticles,cellular uptake,copper ions,fluorescence quenching,amino-functionalized graphene quantum dots
更新于2025-09-11 14:15:04
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Carbon quantum dots derived by direct carbonization of carbonaceous microcrystals in mesophase pitch
摘要： Aggregation of the central aromatic ring system of asphaltene molecules due to π–π interaction can lead to the formation of carbon quantum dots (CQDs). However, to date, such a roadmap has not been demonstrated. Here, we present a simple approach to the synthesis of CQDs by direct carbonization of dispersed carbonaceous microcrystals in mesophase pitch. The size of the as-prepared CQDs is modulated by adjusting the nucleation temperature for mesophase formation. Due to the oxygen-free character, the CQDs exhibit excitation-independent fluorescent behavior with a quantum yield up to 87%. The CQDs were successfully applied to fluorescent detection of Fe3+ ions with good specificity and sensitivity. Our results not only provide a scalable production of CQDs at low cost, but also give valuable clues to understand the solidification of asphaltene at nanoscale.
关键词： Fe3+ ions,carbonization,mesophase pitch,fluorescent detection,carbon quantum dots
更新于2025-09-11 14:15:04
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Incorporation of Nickel Ions to Enhance Integrity and Stability of Perovskite Crystal Lattice for High-Performance Planar Heterojunction Solar Cells
摘要： Enhancement of integrity and stability of crystal lattice are highly challenging for poly-crystalline perovskite films. In this work, a nickel (Ni) ions incorporation strategy is presented to modulate the crystal structure of CH3NH3PbI3 perovskite film. A broad range of experimental characterizations reveal that the incorporation of Ni ions can substantially eliminate the intrinsic halide vacancy defects since Ni ions have a strong preference for octahedral coordination with halide ions, resulting in improved integrity and short-range order of crystal lattice significantly. Moreover, it is also demonstrated that the stronger chemical bonding interaction between Ni ions and halide ions as well as organic group can improve the stability of perovskite material. Simultaneously, the surface morphology of perovskite thin film is also improved by incorporation of nickel ions. As a result, the 1.5% Ni-incorporated planar heterojunction perovskite solar cell exhibits a power conversion efficiency of 18.82%, which is improved by 25% compared with 14.92% for the pristine device. Simultaneously, the 1.5% Ni- incorporated device shows remarkable stability with 90% of the initial efficiency after storage in air environment for 800 h. The studies provide a new insight for metal-incorporated perovskite materials for various optoelectronic applications.
关键词： Ni ions,crystal lattice,Perovskite Solar Cells,MAPbI3,iodine vacancy defects
更新于2025-09-11 14:15:04
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Negative ion characterization in a helicon plasma source for fusion neutral beams by Cavity Ring-Down Spectroscopy and Langmuir Probe laser photodetachment
摘要： Negative ions are characterized in the helicon plasma source RAID (Resonant Antenna Ion Device) at the Swiss Plasma Center by means of Cavity Ring-Down Spectroscopy (CRDS) and Langmuir Probe (LP)-assisted laser photodetachment. A high density and axially homogeneous plasma column is produced via a RF antenna able to sustain the propagation of helicon waves in a steady state regime. An electron density ne ≈ 2.0 × 1018 m?3 in H2 plasma at 0.3 Pa and 3 kW of input power is measured in the center of the plasma column by LP and microwave interferometry. The electron temperature pro?le is peaked on axis reaching Te ≈ 5 eV and decreasing to 1.5 eV at r = 0.05 m. Thus, a hot core region forms where H2 molecules are rovibrationally excited (H2(ν)), and a cold edge, where low energy electrons can attach to H2(ν) and produce H? ions by dissociative attachment. In this work we use LP-assisted laser photodetachment and CRDS diagnostics to measure H? and D? radial density pro?les and how they depend on source parameters. We show that negative ions are distributed on a shell of 0.06 m radius with a peak value of ～ 2.0 × 1016 m?3 in H2 plasma. These results suggest that, although substantial technical development is needed, helicon plasmas could be considered as a possible candidate as sources of negative ions for future NBIs.
关键词： laser photodetachment,Cavity Ring-Down Spectroscopy,helicon plasma source,Langmuir Probe,Negative ions
更新于2025-09-11 14:15:04
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Modification of cellulose fibers with inorganic luminescent nanoparticles based on lanthanide(III) ions
摘要： This article presents synthesis and properties of the fibers modified with luminescent, inorganic nanoparticles doped with lanthanide(III) ions, i.e. LaF3:Ce3+, Gd3+, Eu3+, CeF3:Tb3+ and CePO4:Tb3+. The fibers with luminescent properties were prepared via so called Lyocell process. This method involves dissolving cellulose in aqueous solution of N-methylmorpholine-N-oxide (NMMO) and a subsequent spinning of the fibers, using a dry-wet method. Thanks to the successful incorporation of the modifier nanoparticles (NPs) into the cellulose matrices, the fibers exhibited bright, multicolor emission upon UV irradiation and good mechanical properties, which allowed further textile processing. This type of fibers, as well as the as-prepared textiles/fabric can be used as an anti-counterfeiting agent for clothes and documents protection.
关键词： Lanthanide(III) ions,Luminescence,Multifunctional cellulose fibers
更新于2025-09-11 14:15:04
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Investigation of luminescence mechanism of Nd3+-doped calcium aluminate glasses: Effect of glass-formers
摘要： The relationship between the luminescence properties and the glass structure of Nd3+-doped CaO-Al2O3-(B2O3, SiO2, or Ga2O3) glasses are investigated. The luminescence properties of CaO-Al2O3-B2O3 system are twice as much as that of the CaO-Al2O3-(SiO2 or Ga2O3) system. The glass structure and the coordination environment of the Nd3+ ions were investigated using nuclear magnetic resonance, Raman and electron paramagnetic resonance spectroscopy. All Al, Ga, and Si atoms are four coordinated. The B atoms have three- and four-coordinated boron units, however, most of them are three coordinated. The hyper?ne sublevel correlation spectra reveal that the Al and B nuclei are in the coordination sphere of Nd3+ ions for aluminoborate glasses; however, only 27Al signals could be observed for aluminosilicate and aluminogallate glasses. Owing to the increased number of AlO4-BO3 connections and 11B nuclei around the Nd3+ ions, B has a signi?cant e?ect on the luminescence properties of the Nd3+ ions. The increase in GaO4 or SiO4 does not change the three dimensional-tetrahedral network, and the coordination environment of Nd3+ ions varies slightly. Thus, the e?ect of Ga2O3 and SiO2 on the luminescence properties of the Nd3+ ions is not as great as that of B2O3.
关键词： Glass structure,Local environments of rare-earth ions,EPR,Luminescence properties,NMR
更新于2025-09-10 09:29:36