- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Harnessing polymer grafting to control the shape of plasmonic nanoparticles
摘要： Matrix-free polymer grafted nanoparticles (NPs) are single component polymer nanocomposites (PNCs) for which the often reported severe aggregation of the conventional PNCs can be suppressed. For a given particle core, the size and shape of the polymer grafted nanoparticles can be controlled by the molecular weight of the polymer and its grafting density. However, the degree of homogeneity of one-component PNCs depends on the grafted chain molecular weight and grafting density, as well as on the shape of grafted NPs. Surface plasmon resonance enhanced dynamic light scattering from very dilute solutions, yielding both translational and rotational transport coefficients, complemented by UV–Vis extinction spectra, can detect deviations from spheres. Here, we report that poly(isobutylene)-grafted Ag NPs strongly deviate from the spherical shape and are modeled as prolate spheroids. This NP asphericity, due to inhomogeneous grafting, can impact the structure and properties of plasmonic PNCs in the solid state. Thus, characterizing this behavior is a crucial step prior to the formation of one-component PNCs.
关键词： shape control,polymer grafting,dynamic light scattering,UV–Vis extinction spectra,plasmonic nanoparticles
更新于2025-09-23 15:21:01
-
Effect of fruit moving speed on online prediction of soluble solids content of apple using Vis/NIR diffuse transmission
摘要： The effect of fruit moving speed on online prediction of soluble solids content (SSC) of “Fuji” apples based on visible and near-infrared (Vis/NIR) spectroscopy was studied. Diffuse transmission spectra between 615 and 1,045 nm were collected with a commercial online system at speeds of 0.3 m/s (S1), 0.5 m/s (S2), and 0.7 m/s (S3). Compensation models for SSC of each speed alone (local models) and all speeds (global model) were established using partial least squares (PLS). For global model, spectra of each sample were divided into three parts (P1, P2, and P3), three kinds of spectra partition combinations (P12, P13, and P23) were established. Results showed that S3 performed better and the influence of speed on spectra greatly affected SSC evaluation accuracy between local models. Comparatively, global model was insensitive to fruit moving speed variation and effective wavelengths (EWs) selected by competitive adaptive reweighted sampling (CARS) after Savitzky–Golay smoothing (SGS) achieved better results than local models. Importantly, 36 EWs selected by CARS after SGS of global-P13 model achieved the best results with rp and RMSEP of 0.8419, 0.8895, 0.8948 and 0.6281, 0.5318, 0.5196(cid:1)Brix, respectively. Generally, global-P13 model with EWs is promisingly applied to online SSC prediction of apple by Vis/NIR diffuse transmission.
关键词： soluble solids content,online prediction,effective wavelengths,competitive adaptive reweighted sampling,partial least squares,fruit moving speed,apple,diffuse transmission,Vis/NIR spectroscopy
更新于2025-09-23 15:21:01
-
Luminescence of Phosphate Glasses: P2O5-ZnO-BaF2-K2TeO3-Al2O3-Nb2O5 Doped with Sm3+ Ions for Display and Laser Material
摘要： Luminescent phosphate glasses having the composition 40P2O5-30ZnO-20BaF2-3.8K2TeO3-1.2Al2O3-5Nb2O5 in mol.% doped with 3 9 103 ppm and 4 9 103 ppm Sm2O3 were successfully prepared by a melt-quenching technique. The investigated glasses were characterized by x-ray diffraction, UV–visible–NIR, absorption, emission, and ?uorescence lifetime analysis. The radiative properties were calculated using Judd–Ofelt (J–O) spectral intensity parameters for each of the glasses, which revealed the following trend: X2 > X4 > X6. The J–O intensity parameters were used to evaluate the spontaneous emission properties including branching ratios, transition probabilities, and radiative lifetime. The value of the optical energy band gap was found to decrease with an increase in Sm3+ content, which is explained on the basis of structural changes. The calculated stimulated emission cross-section studied was high, and increased from rSE; at 1.62 lm of glasses 3.81 9 10(cid:2)21 cm2 to 4.38 9 10(cid:2)21 cm2 with increasing Sm3+ ion concentration. The structure of the glasses was investigated by computing Internuclear (cid:3) and ?eld strength F( ) and measurement of Raman spectra.
关键词： refractive index,UV–Vis–NIR,Judd–Ofelt analysis,emission cross-section,Raman spectra,Oxide glasses,density,optical energy gap
更新于2025-09-23 15:21:01
-
Effect of substrate temperature on the properties of RF sputtered CdS thin films for solar cell applications
摘要： We report the effect of substrate temperature (25–300 °C) on the structural, optical and electrical properties of Cadmium Sulphide (CdS) thin films deposited onto glass substrate by Radio Frequency (RF) magnetron sputtering. The structural, morphological, optical and electrical properties of the films were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV–VIS-NIR spectroscopy and Hall Effect measurement respectively. The XRD studies showed that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along the (0 0 2) plane parallel to the substrate surface. The XRD data analysis further revealed the crystallite size of the nanocrystalline films i.e. 22–24 nm exhibiting the fact that crystallite size increased with increasing the substrate temperature. The FE-SEM images along with energy dispersive spectroscopy (EDS) studies confirmed the homogeneous, compact and pin-hole free surface morphology. The UV–VIS-NIR studies unveiled the optical transmittance in the range of 75–90% after 540 nm of the wavelength of light. The optical band gaps were found to be decreasing from 2.34 eV to 2.26 eV with increasing the substrate temperature. The films were characterized as n-type as evidenced by the Hall Effect measurement. The carrier mobility was found to be increasing gradually from 5.53 to 12.57 cm2/V·s by increasing the substrate temperature from room temperature to 300 °C due to the improvement of crystalline quality and grain size of the films. The results showed good optical and electrical properties of the films deposited at 300 °C which are suitable to use as window layer in thin film based solar cells.
关键词： CdS,UV–VIS-NIR,XRD,Hall effect measurement,Thin films,Substrate temperature,RF sputtering
更新于2025-09-23 15:21:01
-
Construction of n-TiO2/p-Ag2O Junction on Carbon Fiber Cloth with Visa??NIR Photoresponse as a Filter-Membrane-Shaped Photocatalyst
摘要： The development of effective and reusable photocatalysts with broad-spectra activity has attracted attention. Herein, we have constructed n-TiO2/p-Ag2O junction on carbon fiber (CF) cloth as an efficient and recyclable photocatalyst. With CF cloth as the substrate, TiO2 nanorods (length: 1–2 μm) are prepared by a hydrothermal process, and the in-situ growth of Ag2O nanoparticles (10–20 nm) is then realized by chemical bath deposition route. The flexible CF/TiO2/Ag2O cloth (area: 4 × 4 cm2) shows a broad and strong photo-absorption (200–1000 nm). Under the illumination of visible-light (λ > 400 nm), CF/TiO2/Ag2O cloth can efficiently eliminate 99.2% rhodamine B (RhB), 99.4% acid orange 7 (AO7), 87.6% bisphenol A (BPA), and 89.5% hexavalent chromium (Cr6+) in 100 min, superior to CF/Ag2O cloth (83.5% RhB, 60.0% AO7, 31.2% BPA and 41.8% Cr6+). In particular, under the NIR-light illumination (980 nm laser), CF/TiO2/Ag2O cloth can remove 70.9% AO7 and 60.0% Cr6+ in 100 min, which are significantly higher than those by CF/Ag2O cloth (19.8% AO7 and 18.9% Cr6+). In addition, CF/TiO2/Ag2O cloth (diameter: 10 cm), as a filter-membrane, can effectively wipe off 94.4% flowing RhB solution (rate: ~ 1 L h? 1) at 6th filtering/degrading grade. Thus, CF/TiO2/Ag2O cloth can be used as a Vis–NIR-responded filter-membrane-shaped photocatalyst with high-efficiency for purifying wastewater.
关键词： n-TiO2/p-Ag2O junction,Filter-membrane,Photocatalyst,Vis-NIR photoresponse,Carbon fiber cloth
更新于2025-09-23 15:21:01
-
Fluorescence quenching of molybdenum disulfide quantum dots for metal ion sensing
摘要： In the present work, we have used hydrothermally synthesized in situ functionalized MoS2-QDs for a sensitive (limit of detection ~ 2.06 μM) and selective detection of Fe3+ ions. A detailed study of fluorescence quenching behavior for MoS2-QDs in the presence of Fe3+ ions has been performed using the Stern–Volmer plot, modified Stern–Volmer plot, and time-resolved photoluminescence measurements. Absorption based titration spectra and time-resolved photoluminescence measurements confirmed the fluorescence quenching is static with three decay times originated from the three different fluorescing sites. Interestingly, it is found that emission spectra consist of three bands at positions ~ 450 nm (P1, ~ 2.76 eV), ~ 475 nm (P2, ~ 2.61 eV), and ~ 503 nm (P3, ~ 2.46 eV). These peaks show a systematic quenching with the increasing concentration of Fe3+ ions. Quenching constants corresponding to these emission bands are found of the order of ~ 103 M?1. Large values of bimolecular quenching constants (~ 1011 M?1 s?1) suggest a strong binding interaction between MoS2-QDs and Fe3+ ions. Furthermore, to understand the fluorescence quenching of MoS2-QDs in the presence of Fe3+ ions, a ground-state complex formation-based mechanism has been proposed and elucidated in detail.
关键词： Nanostructures,UV/Vis spectroscopy,Metal ion sensing,Time-resolved photoluminescence,Fluorescence spectroscopy
更新于2025-09-23 15:21:01
-
Copper nanoparticles enhanced luminescence of Eu3+ doped lead tellurite glass ceramics
摘要： Structural, optical and magnetic properties of some lead tellurite glass ceramics doped with europium(III) ions and co-doped with fixed amounts of metallic copper nanoparticles (CuNPs) or copper(II) ions (via CuO) were investigated. Samples in the (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuNPs)0.3 and (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuO)0.3 systems with 0 ≤ x ≤ 10 mol% were obtained and investigated for the first time. Several techniques such as X-ray diffraction, UV-VIS, EPR and luminescence spectroscopies and density and magnetic susceptibility measurements were used in order to characterize the samples. XRD data show that the samples with low Eu2O3 contents (x ≤ 1 mol%) are amorphous while for higher europium oxide contents (x > 1 mol%) are glass ceramics. They also reveal that increasing the Eu2O3 content of samples the symmetry around the europium ions changes from face centered cubic to monoclinic. These symmetry changes are confirmed by the photoluminescence data. In addition, photoluminescence data show that the co-doping with metallic copper nanoparticles enhances the emission peaks of europium ions. UV-VIS absorption spectra show the presence of six coordinated copper (II) ions located at sites with a distorted octahedral symmetry. The EPR data confirm the presence of copper (II) ions in all the studied samples. Magnetic susceptibility measurements suggest the presence of europium ions in both their 3+ and 2+ valence states and evidence an important clustering tendency of europium ions even for low Eu2O3 contents.
关键词： EPR,UV-VIS,Photoluminescence,Magnetic susceptibility,Lead-tellurite glass ceramics,XRD
更新于2025-09-23 15:21:01
-
Synthesis, DFT studies, fabrication, and optical characterization of the [ZnCMC] <sup>TF</sup> polymer (organic/inorganic) as an optoelectronic device
摘要： A novel carboxymethyl cellulose zinc thin film [ZnCMC]TF was fabricated using the sol–gel technique. Different characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and the optical properties were used to study the properties of [ZnCMC]TF. The molecular structure, FTIR, and optical properties were optimized. The Raman spectrum of the [ZnCMC]TF complex shows several bands in the range of 72–556 cm?1 due to (nZn–O) stretching and (Zn–O) bending, which is an obvious distinction between the FTIR and Raman spectra of [ZnCMC]TF. The optimization was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. The chemical structure was confirmed by spectroscopic and structural properties for both CMC and [ZnCMC]TF; the XRD results showed the same crystal structure (Monoclinic 2). [ZnCMC]TF has a larger grain size than CMC and has a similar behavior in the optical gap energy. The optical constants increased with increasing photon energy, refractive index n, absorption index k, and optical conductivity. The SEM images provide very good evidence in favor of the reaction of zinc transition metal with CMC for the formation of the [ZnCMC]TF complex. The resulting [CMC] spherical thin film and the [ZnCMC]TF polymeric nanorods were examined by different techniques including TEM and EDX. The optical properties obtained from the simulated FTIR, XRD, and CASTEP are in good agreement with those obtained from the experimental studies on CMC and ZnCMC. Based on the optical findings, [ZnCMC]TF is a promising candidate in applications such as solar cells and optoelectronic devices.
关键词： TEM,DMol3,zinc thin film,carboxymethyl cellulose,UV-Vis,DFT,optoelectronic devices,XRD,EDX,CASTEP,sol–gel technique,SEM,FTIR,optical properties,Raman spectroscopy
更新于2025-09-23 15:21:01
-
[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Investigating the Similarities and Differences among UV/Vis, Infrared, Fluorescence, and Raman Spectroscopies through Discussion of Light–Matter Interactions
摘要： Spectroscopy is an invaluable tool in chemistry and is introduced throughout the undergraduate curriculum. At the fundamental level, spectroscopy measures the interactions between electromagnetic radiation and matter. Usually, students practice measuring spectra to characterize molecules and analyze experimental results. However, too often, little emphasis is placed on the specific interactions of the electromagnetic radiation with matter, which leads to a lack of differentiation and understanding of applicability among spectroscopic techniques. Here, a discussion of scattering, absorption, and emission processes is used to assist in the understanding of different spectroscopic techniques such as infrared and UV/vis (absorption), fluorescence (emission), and Raman (scattering). The purpose is to provide instructors with different visual frameworks and exercises for the introduction of spectroscopy in the undergraduate classroom and laboratory. The intended outcome is for students to understand the experimental spectroscopic techniques at a deeper level, giving rise to improved critical thinking skills in regards to scientific processes.
关键词： Raman,UV/Vis,Fluorescence,Light–Matter Interactions,Infrared,Spectroscopy
更新于2025-09-23 15:21:01
-
Vis- and NIR-Based Instruments for Detection of Black-Tip Damaged Wheat Kernels: A Comparative Study
摘要： Black-tip (BT) is a non-mycotoxic fungus that attacks wheat kernels, forming a dark brown or black sooty area at the tip of the kernel. Visual inspection, which is the approved reference method for determining the amount of BT in wheat, requires substantial time and has high potential for subjective evaluation. Three spectrometers covering the spectral ranges 950-1636 nm (Spec1), 600-1045 nm (Spec2), and 380-780 nm (Spec3) were evaluated for their ability to predict the presence of BT. Kernels were quantified into four levels: (A) sound, (B) low black-tip symptoms (BTS), (C) high BTS, and (D) BT damaged (BTD). Discriminant classification models were developed to evaluate combinations of levels. The combinations were (1) levels A, B, C, and D separately; (2) A, B+C, and D; and (3) A+B and C+D. Spectral data for 2,760 kernels obtained from 23 hard red winter (HRW) wheat samples, each comprising 30 kernels that were visually selected for each of the four levels of black-tip severity (A, B, C, and D), were collected with each spectrometer. Discriminant calibration models for each spectrometer and classification category were developed based on (1) three combinations of 17 HRW wheat samples, with the six remaining samples used for independent validation, and (2) combinations of 20 randomly selected kernels from each of the 23 HRW wheat samples as calibration samples, with the remaining ten kernels used as validation samples. Discriminant analysis was based on five wavelengths for each model. Spectra pretreatment was the standard normal variate (SNV). Results showed that all three spectrometers were capable of detecting BT damage on wheat kernels. BT classification accuracy was observed to have been affected by wheat varieties for Spec1 and Spec2 (both with NIR wavelengths) but not for Spec3, which was entirely in the visible region. The two-category classification (A+B, C+D) provided higher accuracy than the three-category (A, B+C, D) and four-category (A, B, C, D) classifications. Based on the percent correct classification and Youden’s index, Spec2 performed better in detecting sound and BTD wheat kernels, with classification accuracies of the best two-category classification calibration model ranging from 85.6% to 87.5%, compared to Spec1 at 74.8% to 78.4% and Spec3 at 76.7% to 79.2%. This study also showed the potential of using a five-wavelength model, which equates to the potential for developing simple, less expensive, high-speed photoelectric detection instruments. These instruments can serve as important tools in plant breeding, grading, or grain processing facilities to enable BT detection and, with proper selection of wavelengths, may also find applications in simultaneous single-kernel detection, measurement, and segregation of other chemical characteristics, such as protein and starch content.
关键词： Black-tip damage,Wheat,VIS,NIR,Spectroscopy
更新于2025-09-23 15:21:01