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Tunable emission of LiCa3MgV3O12:Bi3+ via energy transfer and changing excitation wavelength
摘要： LiCa3MgV3O12:Bi3+ phosphor is successfully synthesized by the high-temperature solid-state reaction method in air. The crystal structures and luminescence properties are investigated. Excitation/emission bands of LiCa3MgV3O12:Bi3+ phosphor show red-shift with increasing the monitored/excitation wavelengths from short to long. The doping of Bi3+ ion can result in the host LiCa3MgV3O12 lattice distortion and the energy transfer to Bi3+. The tunable emission of LiCa3MgV3O12:Bi3+ phosphor from blue-green to yellow can be observed with increasing Bi3+ concentration from 0 to 8 mol%. The chromaticity coordinates of LiCa(3-x)MgV3O12:xBi3+ phosphors can change from (0.2393, 0.3260) to (0.4358, 0.4472) with increasing Bi3+ concentration from 0 to 8 mol%. The existence of VO4 3? → Bi3+ ET in LiCa3MgV3O12:Bi3+ phosphor is indicated by the luminescence properties. The luminous mechanism of LiCa3MgV3O12:Bi3+ phosphor is explained by the con?gurational coordinate diagrams of VO4 3? and Bi3+. The experimental results are helpful for the luminescence property researches of other Bi3+-doped luminescence materials.
关键词： Energy transfer,Tunable emission,LiCa3MgV3O12: Bi3+ ions,Vanadates
更新于2025-09-10 09:29:36
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Influence of the Tb3+ concentration on the luminescent properties of high silica glass
摘要： Tb3+- doped high silica glass was prepared by sintering porous glass. The density, valence state and amount of Tb, transmittance, photoexcitation spectra, photoluminescence spectra, and cathodoluminescence spectra (CL) were recorded and the luminescence decay kinetics analyzed in details. These results show that the doping concentration in high silica glass is in direct proportion to the concentration in solution, and the density increases with the increasing concentration of rare earth ions as well as the intensity of emission spectrum. The largest emission intensity of 0.2 mol/L is more than 2 times higher than the intensity of the 0.05 mol/L. Besides, the “red” shift phenomenon could be distinguished clearly in the transmittance spectra. There is a broad band at the “red” region in the CL spectra. The decay time which is in the millisecond range in di?erent spectral range were measured and analyzed revealing that the decay time of 5D3 is shorter than that of 5D4.
关键词： Luminescent properties,Rare earth ions,High silica porous glass
更新于2025-09-10 09:29:36
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β-Cyclodextrin protected gold nanoparticle based cotton swabs as an effective candidate for specific sensing of trace levels of cyanide
摘要： In recent work, we demonstrate a rapid colorimetric and easy visual determination of cyanide ions (CNˉ ions) in water based on gold nanoparticles stabilized with β-cyclodextrin (β-CD). Optical detection of CNˉ ions were carried out using β-CD-AuNPs by tracking the changes in the SPR band and colorimetric nature of the β-CD AuNPs. This colorimetric nanosensor capably and ultra sensitively distinguishes the CNˉ ions owing to the capacity of etching the β-CD AuNPs surface and form a stable water soluble Au-CN complex. Under investigational conditions, the colorimetric assay demonstrated a steady response for CNˉ ions over a concentration arrays from 4.50 × 10-6 to 99.00 × 10-6 mol dm-3 with R = 0.994. Lowest limit of detection of this economical, naked eye visual approach is 93.00 × 10-9 mol dm-3, which is under the tolerant limit value (1.90 × 10-6 mol dm-3) described by the World health organization in drinking water. Specificity of β-CD-AuNPs based optical platform for the detection of CNˉ ions is superb evaluated with the various potential interfering anions. Furthermore, the proposed β-CD-AuNPs nanoprobe is effectively applied to quantify the CNˉ ions in tap and drinking water samples. For convenient use, we have designed a very stable β-CD-AuNPs containing cotton swab and it revealed good sensitivity against CNˉ ions in the environment with only bare eye.
关键词： cotton swab,Colorimetric analysis,drinking water samples,cyanide ions,nanosensor
更新于2025-09-10 09:29:36
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Multi-diagnostic setup to investigate the two-close-frequency phenomena
摘要： While the mechanism is still not fully clear, the beneficial effect (higher intensity of highly charged ions, stable plasma conditions) of the second microwave injected to the ECR plasma was observed in many laboratories, both with close and far frequencies. Due to the complexity of the phenomena (e.g. interaction of resonant zones, damped instabilities) complex diagnostic methods are demanded to understand its mechanism better and to fully exploit the potential hidden in it. It is a challenging task since complex diagnostics methods require the arsenal of diagnostic tools to be installed to a relatively small size plasma chamber. Effect of the injected second 13.6–14.6 GHz microwave to the 14.25 GHz basic plasma has been investigated by means of soft and (time-resolved) hard X-ray spectroscopy, by X-ray imaging and space-resolved spectroscopy and by probing the rf signals emitted by the plasma. Concerning the characterization of the X radiation, in order to separate the source and position of different X-ray photons special metallic materials for the main parts of the plasma chamber were chosen. A detailed description and explanation of the full experimental setup and the applied non-invasive diagnostics tools and its roles are presented in this paper.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),X-ray detectors,Plasma diagnostics - interferometry, spectroscopy and imaging,Plasma generation (laser-produced, RF, x ray-produced)
更新于2025-09-09 09:28:46
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On the efficient Te4+→Yb3+ cooperative energy transfer mechanism in tellurite glasses: A potential material for luminescent solar concentrators
摘要： Te4+/Yb3+ co-doped 80%TeO2-20%Li2O glasses (amounts in mol%) were prepared by the conventional melt-quenching method in an ambient atmosphere, in order to investigate their optical characteristics for application in solar cells. An efficient near-infrared down-conversion mechanism was observed in these samples, involving the emission of two near infrared photons (at around 978 nm) after the absorption of one photon in the ultraviolet-blue region. This effect occurred by means of a process of cooperative energy transfer (CET) from Te4+ to Yb3+ ions. The CET efficiency (h CET) was calculated from radiative transitions (lifetime) and also by a new method, developed in this work, based on rate equations quantifying the non-radiative transitions (thermal effect) involved in the system. The two methods showed very good agreement, with h CET between 82-100% obtained for the sample prepared using a higher Yb3+ concentration (4 mol%). The results suggested that these tellurite materials could have potential applications in improving the efficiency of silicon-based solar cells.
关键词： Te4+ ions,Thermal lens effect,Tellurite glass,Yb3+ ions,Down-conversion,Cooperative energy transfer
更新于2025-09-09 09:28:46
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Rapid immunological detection of copper ions using fluorescence immunochromatographic assay
摘要： One-step fluorescence immunochromatographic assay (FICA) has been developed using fluorescent microspheres-labelled monoclonal antibody (McAb) probe for the rapid detection of copper ions in herbal plants and soil samples were investigated in this study. The results can be read by the fluorescence reader according to the fitted standard curve equation. Under optimal conditions, detecting copper ions with FICA can be done within 15 min with a LOD (limit of detection) of 0.2 μg/L, and was very useful for the rapid onsite testing. A total of 31 solid samples were pre-treated by microwave digestion combined with cation exchange solid phase extraction and prepared as test samples for FICA and ICP-AES. The two methods showed good relativity with correlation coefficients of 0.924 and 0.969 in herbal plants and soil samples for copper detection, respectively. We hope that our research can help promote the daily monitoring of heavy metal pollution effectively.
关键词： Copper ions,fluorescence immunochromatographic assay,monoclonal antibody,rapid onsite testing
更新于2025-09-09 09:28:46
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ions
摘要： Laser-produced Sn plasma sources are used to generate extreme ultraviolet light in state-of-the-art nanolithography. An ultraviolet and optical spectrum is measured from a droplet-based laser-produced Sn plasma, with a spectrograph covering the range 200–800 nm. This spectrum contains hundreds of spectral lines from lowly charged tin ions Sn1+?Sn4+ of which a major fraction was hitherto unidenti?ed. We present and identify a selected class of lines belonging to the quasi-one-electron, Ag-like ([Kr]4d 10 nl electronic con?guration), Sn3+ ion, linking the optical lines to a speci?c charge state by means of a masking technique. These line identi?cations are made with iterative guidance from COWAN code calculations. Of the 53 lines attributed to Sn3+, some 20 were identi?ed from previously known energy levels, and 33 lines are used to determine previously unknown level energies of 13 electronic con?gurations, i.e., 7p, (7, 8)d, (5, 6)f , (6–8)g, (6–8)h, (7, 8)i. The consistency of the level energy determination is veri?ed by the quantum-defect scaling procedure. The ionization limit of Sn3+ is con?rmed and re?ned to 328 908.4 cm?1, with an uncertainty of 2.1 cm?1. The relativistic Fock-space coupled-cluster (FSCC) calculations of the measured level energies are generally in good agreement with experiment but fail to reproduce the anomalous behavior of the 5d 2D and nf 2F terms. By combining the strengths of the FSCC calculations, COWAN code calculations, and con?guration interaction many-body perturbation theory, this behavior is shown to arise from interactions with doubly excited con?gurations.
关键词： Sn3+ ions,energy-level structure,nanolithography,laser-produced plasma,extreme ultraviolet light
更新于2025-09-09 09:28:46
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x-ray transitions in Cu- and Ni-like tungsten ions
摘要： The 4d → 3p x-ray transitions in Cu- and Ni-like tungsten ions have been studied theoretically. The multicon?guration Dirac-Hartree-Fock (MCDHF) method and the large-scale relativistic con?guration-interaction (CI) method have been employed in order to take into account electron correlation effects on the wavelengths and transition rates. It was found that the wavelengths and transition rates obtained from the MCDHF-CI method depend strongly on the size and the type of the active space used in the calculations. It has been found that extending the active space of orbitals without careful control of the con?guration state function base does not always lead to good quality MCDHF-CI results for highly ionized tungsten ions.
关键词： x-ray transitions,CI,electron correlation,MCDHF,tungsten ions
更新于2025-09-09 09:28:46
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Scaling relations of the time-dependent Dirac equation describing multiphoton ionization of hydrogenlike ions
摘要： Approximate scaling laws with respect to the nuclear charge are introduced for the time-dependent Dirac equation describing hydrogenlike ions subject to laser fields within the dipole approximation. In particular, scaling relations with respect to the laser wavelengths and peak intensities are discussed. The validity of the scaling relations is investigated for two-, three-, four-, and five-photon ionization of hydrogenlike ions with nuclear charges ranging from Z = 1 to 92 by solving the corresponding time-dependent Dirac equations adopting the properly scaled laser parameters. Good agreement is found and thus the approximate scaling relations are shown to capture the dominant effect of the response of highly charged ions to intense laser fields compared to that of atomic hydrogen. On the other hand, the remaining differences are shown to allow for the identification and quantification of additional, purely relativistic effects in light-matter interaction.
关键词： scaling laws,time-dependent Dirac equation,relativistic effects,hydrogenlike ions,multiphoton ionization
更新于2025-09-09 09:28:46
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Bandgap opening in graphene using alkali ions by first principles
摘要： Recently, bandgap opening at the Dirac point in graphene, formed on SiC(0001) surfaces, has been reported in different experiments, by deposition of positively charged alkali ions. This is clearly of great relevance for the countless practical applications of graphene in nano-electronic devices. By first principles calculations, based on the Density Functional Theory, the electronic band structure and the energetic properties are obtained for Na+, K+, and Cs+ ions interacting with graphene on SiC. We show that simple adsorption of alkali ions on intact graphene cannot give rise to a significant energy gap. An appreciable bandgap opening, similar to that observed in actual experiments, occurs instead due to the formation of Stone-Wales defects and substitutional defects (where positively charged alkali ions replace carbon atoms) that lead to a significant breaking of the charge symmetry among the carbon atoms of pristine graphene.
关键词： bandgap opening,graphene,alkali ions,Stone-Wales defects,substitutional defects,Density Functional Theory,first principles
更新于2025-09-09 09:28:46