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Plasmonic Nanocavity Metasurface Based on Laser-Structured Silver Surface and Silver Nanoprisms for the Enhancement of Adenosine Nucleotide Photoluminescence
摘要： A reliable photoluminescence (PL) spectroscopy and imaging of biomolecules at room temperature is a challenging and important problem of biophysics, biochemistry, and molecular genetics. A unique effect of strong plasmonic enhancement of the PL by metal nanostructures is one of the most effective approaches for this purpose. The highest enhancement is provided by metal nanostructures with densely packed sharp tips, periodically arranged metal nanostructures, and plasmonic cavities. All of these features have been realized in the plasmonic cavity metasurface based on the silver (Ag) laser-induced periodic surface structure and Ag triangular nanoprisms studied in the present work. The strong plasmon-enhanced PL of 5′-deoxyadenosine monophosphate deposited on such metasurfaces has been revealed at room temperature. The observed enhancement of more than 1000-fold has been interpreted as a result of synergetic action of the generation of a high concentration of hot spots near the sharp edges of the laser-induced surface structure and nanoprisms together with excitation of the collective gap mode of the cavity due to strong near-field plasmonic coupling. Correspondingly, the plasmonic cavity metasurfaces consisting of metal laser-induced periodic surface structures and nonspherical metal nanoparticles with sharp edges have been shown to be crucial for the highly sensitive detection and imaging of biomolecules at room temperature without consuming any dye labels.
关键词： hot spots,plasmon gap mode,plasmonic metasurface,near-field coupling,nucleotide photoluminescence enhancement
更新于2025-11-19 16:46:39
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Creating Orientation-Independent Built-In Hot Spots in Gold Nanoframe with Multi-Breakages
摘要： In this study, the plasmonic extinction spectra and local field distributions of three different gold nanoframe models with multi-breakages are simulated based on the discrete dipole approximation (DDA) method. By tuning the length of one breakage, there are two clearly separated surface plasmon resonance (SPR) peaks which show a clear blue shift as the broken length increases, and the local field enhancement factor reaches a maximum of 140.8 when the broken length is 2 nm. The changing of plasmonic field interaction and the increased restoring force may be used to explain the resonance blue shift. In these three models, the three-dimensional (3D) local electric field distributions confirm that the hot spot regions mainly concentrate on the interior broken surfaces when the incident electric field is polarized along the broken edge. Moreover, the gold nanoframe with three breakages can create the polarization orientation-independent built-in hot spots inside the broken surfaces. Therefore, the local field enhancement and hot spot regions may be controlled by adjusting the number of breakages and the orientation of polarized field. Consequently, these simulated results about the plasmonic optical properties in gold nanoframe provide a theoretical guidance for the design of polarization orientation-independent SERS substrate, which could create the built-in hot spots and improve the SERS activity.
关键词： Multi-breakages,Gold nanoframe,Polarization direction,Hot spots
更新于2025-09-23 15:22:29
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Surface-nanostructured single silver nanowire: a new one-dimensional microscale SERS interface
摘要： One-dimensional microscale SERS-active interfaces have been intriguing as a newly emerging class of SERS interfaces compared to conventional macroscale SERS substrates. In this work, a stable surface-nanostructured single silver nanowire was fabricated. The nanostructures on the nanowire are formed by nanoscale silver crystal dots with diameters of 20-50 nm. The SERS signals of the crystal violet probe molecules adsorbed on the nanostructures are dramatically enhanced by both electromagnetic and chemical effects. The hot spots generated at the junctions of adjacent nanoscale dots yield highly efficient surface plasmon resonance. Simultaneously, the charge transfer on the atomic-scale silver cluster located at the nanostructured interface causes an enhancement similar to a Raman resonance. The intensity distributions of the SERS peaks on the surface-nanostructured single nanowire are characterized by SERS mapping. It is found that, although the intensities of the SERS peaks are different, their SERS mapping images show uniform SERS enhancement distributions, whereas the noticeable SERS intensity distributions on the single smooth silver nanowire are mainly located on the two ends of the nanowire. The large number of nanoscale crystal dots along with the atomic-scale silver clusters are uniformly and densely distributed on the surface of the single roughened nanowire; these structural attributes induce a uniform and large surface plasmon resonance and charge transfer enhancements on the entire surface of the nanowire. This work indicates that the surface-nanostructured single silver nanowire, synthesized using a quite simple preparation method, performs as an excellent one-dimensional microscale SERS substrate with uniform and high enhancement characteristics, which shows high potential for applications as a new class of SERS-active substrates. Furthermore, the higher enhancement factor of the microscale SERS interfaces can be achieved by introducing other roughened nanowires to assemble a dimer and a trimer as micro SERS substrates, which is consistent with the dark field (DF) measurements.
关键词： Hot spots,Raman,Micro SERS interfaces,Charge transfer,Silver nanowire
更新于2025-09-23 15:21:21
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Photovoltaic Degradation Rate Affected by Different Weather Conditions: A Case Study Based on PV Systems in the UK and Australia
摘要： This article presents the analysis of degradation rate over 10 years (2008 to 2017) for six different photovoltaic (PV) sites located in the United Kingdom (mainly affected by cold weather conditions) and Australia (PV affected by hot weather conditions). The analysis of the degradation rate was carried out using the year-on-year (YOY) degradation technique. It was found that the degradation rate in the UK systems varies from ?1.05% and ?1.16%/year. Whereas a higher degradation ranging from ?1.35% to ?1.46%/year is observed for the PV systems installed in Australia. Additionally, it was found that in the Australian PV systems multiple faulty PV bypass diodes are present due to the rapid change in the ambient temperature and uneven solar irradiance levels influencing the PV modules. However, in cold weather conditions (such as in the Northern UK) none of the bypass diodes were damaged over the considered PV exposure period. Furthermore, the number of PV hot spots have also been observed, where it was found that in the UK-based PV systems the number of hot spotted PV modules are less than those found in the Australian systems. Finally, the analysis of the monthly performance ratio (PR) was calculated. It was found that the mean monthly PR is equal to 88.81% and 86.35% for PV systems installed in the UK and Australia, respectively.
关键词： performance analysis,photovoltaic systems,performance ratio,degradation,hot-spots
更新于2025-09-23 15:21:01
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Understanding partial shading effects in shingled PV modules
摘要： Shingled solar modules are one of several technologies currently being considered to obtain higher solar module efficiencies. Using equivalent circuit modelling this paper investigates the robustness of shingled modules to partial shading with respect to the power produced and the power dissipated in shaded shingles. The modeling results are experimentally verified. We find that power losses in shingled modules can be larger than in conventional modules for similar shading conditions. The risk of significant local heating resulting from partial shading, potentially leading to catastrophic module failure can also be higher in shingled modules due to the substantially higher reverse biases experienced by shaded shingles. Both risks can effectively be mitigated by operating each shingled module at its own maximum power point, for instance by using module level power electronics on each module or by incorporating a sufficient number of bypass diodes into the module design.
关键词： Partial shading,High efficiency modules,Hot spots,Modelling,Shingled modules
更新于2025-09-23 15:21:01
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The analysis on simulation and invalidation of hot-spot temperature distribution in micro-defective crystalline silicon solar cells
摘要： According to the distribution of reverse biased leakage current of micro-defective solar cells, the mathematic models of the hot spot thermal power of photovoltaic(PV) modules are established. The uniform and non-uniform distribution of thermal power in hot spot solar cell are theoretically calculated and experimentally analyzed in different shading conditions. Based on the model, the hot spot temperature distribution of different defective cells is simulated by ANSYS software. Then a novel experimental platform is set up to validate the simulation results in outdoor conditions. The mechanism of hot spot failure and the worst hot spot condition are analyzed. According to the results of experiment and simulation, the relative deviation between simulation and experimental data is less than 10% through the model proposed in this paper. Furthermore, in the normal modules, according to the result of simulation and experiment, the worst case of hot spots happens when the heat power is maximum and the shading ratio is about 10-20%. In the defective modules, it happens when the heat power is not maximum and the shading ratio is about 50-60%.
关键词： reliability,non-uniform distribution,Hot spots,micro-defective solar cells
更新于2025-09-16 10:30:52
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Sandwiching analytes with structurally diverse plasmonic nanoparticles on paper substrates for surface enhanced Raman spectroscopy
摘要： This report describes the systematic combination of structurally diverse plasmonic metal nanoparticles (AgNPs, AuNPs, Ag core–Au shell NPs, and anisotropic AuNPs) on flexible paper-based materials to induce signal-enhancing environments for surface enhanced Raman spectroscopy (SERS) applications. The anisotropic AuNP-modified paper exhibits the highest SERS response due to the surface area and the nature of the broad surface plasmon resonance (SPR) neighboring the Raman excitation wavelength. The subsequent addition of a second layer with these four NPs (e.g., sandwich arrangement) leads to the notable increase of the SERS signals by inducing a high probability of electromagnetic field environments associated with the interparticle SPR coupling and hot spots. After examining sixteen total combinations, the highest SERS response is obtained from the second layer with AgNPs on the anisotropic AuNP paper substrate, which allows for a higher calibration sensitivity and wider dynamic range than those of typical AuNP–AuNP arrangement. The variation of the SERS signals is also found to be below 20% based on multiple measurements (both intra-sample and inter-sample). Furthermore, the degree of SERS signal reductions for the sandwiched analytes is notably slow, indicating their increased long-term stability. The optimized combination is then employed in the detection of let-7f microRNA to demonstrate their practicability as SERS substrates. Precisely introducing interparticle coupling and hot spots with readily available plasmonic NPs still allows for the design of inexpensive and practical signal enhancing substrates that are capable of increasing the calibration sensitivity, extending the dynamic range, and lowering the detection limit of various organic and biological molecules.
关键词： SERS,surface enhanced Raman spectroscopy,interparticle coupling,microRNA detection,plasmonic nanoparticles,paper substrates,signal enhancement,hot spots
更新于2025-09-16 10:30:52
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Photovoltaic Hot-Spots Fault Detection Algorithm using Fuzzy Systems
摘要： Faults in photovoltaic (PV) modules, which might result in energy loss and reliability problems are often difficult to avoid, and certainty need to be detected. One of the major reliability problems affecting PV modules is hot-spotting, where a cell or group of cells heats up significantly compared to adjacent solar cells, hence decreasing the optimum power generated. In this article, we propose a fault detection of PV hot-spots based on the analysis of 2580 PV modules affected by different types of hot-spots, where these PV modules are operated under various environmental conditions, distributed across the UK. The fault detection model comprises a fuzzy inference system (FIS) using Mamdani-type fuzzy controller including three input parameters, namely, percentage of power loss (PPL), short circuit current (Isc), and open circuit voltage (Voc). In order to test the effectiveness of the proposed algorithm, extensive simulation and experimental-based tests have been carried out; while the average obtained accuracy is equal to 96.7%.
关键词： Fault Detection,Hot-Spots,Photovoltaic,Power Loss,I-V curve,Fuzzy Logic
更新于2025-09-16 10:30:52
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Controlling the Morphologies of Silver Aggregates by Laser-Induced Synthesis for Optimal SERS Detection
摘要： Controlling the synthesis of metallic nanostructures for high quality surface-enhanced Raman scattering (SERS) materials has long been a central task of nanoscience and nanotechnology. In this work, silver aggregates with different surface morphologies were controllably synthesized on a glass–solution interface via a facile laser-induced reduction method. By correlating the surface morphologies with their SERS abilities, optimal parameters (laser power and irradiation time) for SERS aggregates synthesis were obtained. Importantly, the characteristics for largest near-field enhancement were identified, which are closely packed nanorice and flake structures with abundant surface roughness. These can generate numerous hot spots with huge enhancement in nanogaps and rough surface. These results provide an understanding of the correlation between morphologies and SERS performance, and could be helpful for developing optimal and applicable SERS materials.
关键词： laser-induced synthesis,silver aggregates,surface-enhanced Raman scattering,hot spots
更新于2025-09-11 14:15:04
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Nanostructured GaN sensors for Surface Enhanced Raman Spectroscopy
摘要： The aim of this communication is to describe the range of applications of GaN-based platforms for trace detection and identification of biological and chemical agents using SERS technique. The methods of nano-structuring of GaN surface for SERS application are briefly described. The results of employing SERS method for analysis of Fentanyl and Bacillus Atrophaeus spores is demonstrated. The arguments are summarized which show the universal feature of GaN-based platforms as SERS sensor.
关键词： SERS,GaN,Hot-spots,Nanostructure
更新于2025-09-11 14:15:04