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Transition from Two-photon Absorption to Saturable Absorption in Gold Patterned Ruby Thin Film
摘要： Nonlinear behaviour of gold micro disks patterned Ruby film has been investigated via Z-scan technique. Open Z-scan was performed for Ruby and Ruby/gold thin film using 532 nm Laser source. Two-photon absorption (TPA) and Saturable absorption (SA) have been observed in pure Ruby and Ruby/gold thin film respectively. The expression for normalized transmittance in open Z-scan was obtained by Gaussian decomposition method for fitting the open. The values for nonlinear absorption coefficient (β) for Ruby/gold (7.41 × 10?7??/??) was two orders of magnitude higher than that of Ruby (1.41 × 10?9??/??). Further, TPA and SA were confirmed by open Z-scan on these films, performed by 633 nm Laser source.
关键词： Surface Plasmon Resonance,Ruby,Z-scan,Two-photon absorption,Saturable absorption
更新于2025-09-23 15:22:29
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Properties of Au incorporated In2O3 films
摘要： Effect of gold loading on the structural, morphological, optical and electrical properties of RF magnetron sputtered In2O3 films is discussed. Annealing is done to analyse the properties of heavily Au loaded In2O3 film after thermal treatment. Au acts as a nucleation centre and improves the crystalline quality of cubic bixbyite In2O3 films with moderate Au loading concentration. FESEM and AFM images of the as-deposited films present smooth surface morphology with a dense distribution of small grains. Random distribution of Au nanorods can be seen in the FESEM image of the 10 wt% Au incorporated film annealed at a temperature of 400 °C. The present study reveals the formation of smooth, crack-free, crystalline In2O3 films with Au incorporation. XPS analysis suggests the predominance of metallic state of Au in the Au loaded films. Absorption studies show an enhanced absorption in both as-deposited and annealed Au loaded films. Transmittance of In2O3 films is considerably modified but electrical properties are not much modified by Au incorporation. Enhancement in UV luminescence emission of In2O3 films ~378 nm is observed with Au incorporation up to 3 wt%. Intense UV emission in Au incorporated films opens a possibility of using these films for UV light emission applications.
关键词： Au incorporation,In2O3,UV emission enhancement,Au nanoclusters,Surface plasmon resonance
更新于2025-09-23 15:22:29
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Ion beam engineering of morphological, structural, optical and photocatalytic properties of Ag-TiO2-PVA nanocomposite thin film
摘要： Development of plasmonic nanocomposite coatings with tunable optical and photocatalytic properties is important for diverse technological applications. In this paper, we report modifications in the microstructural, optical and photocatalytic properties of Ag-TiO2-PVA nanocomposite thin film by 8 MeV Si3+ ion irradiation. Ag-TiO2-PVA nanocomposite thin films on silica glass were prepared by a combination of sol-gel method and spin coating. Ion irradiation induced morphological evolution of Ag-TiO2-PVA thin film was studied by atomic force microscopy and field emission scanning electron microscopy, which revealed interesting changes in the size distribution of nanostructures with increasing ion fluence. Ion irradiation of the Ag-TiO2-PVA thin film resulted in the emergence of SPR peak of Ag nanoparticles at 456 nm, which shifted to 446 nm along with enhancement in intensity as the ion fluence was increased. Significant enhancement in the photocatalytic efficiency of Ag-TiO2-PVA nanocomposite thin film for degradation of methylene blue was observed upon ion irradiation at 1 × 1013 ions/cm2. The origins of microstructural, morphological, optical and plasmonic modifications and enhancement in the photocatalytic efficiency of Ag-TiO2-PVA nanocomposite thin films have been discussed.
关键词： Ion irradiation,Surface plasmon resonance,Nanocomposite,Photocatalysis,Ag-TiO2-PVA
更新于2025-09-23 15:22:29
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Heterogeneous photocatalyzed C-C cross-coupling reactions under visible-light and near-infrared light irradiation
摘要： With the development of photocatalytic technology and organic synthesis chemistry, the photocatalyzed cross-coupling reaction provides one of the most attractive methodologies for the C-C bond formation and has been booming in recent years. The advantages of the heterogeneous photocatalyzed C-C cross-coupling reaction lie in its environment friendly, easily separated and conveniently recovered catalysts. In this review, we summarized and highlighted recent achievements of heterogeneous photocatalyzed C-C cross-coupling reactions through four aspects: visible light induced C-C cross-coupling reactions catalyzed by Pd supported semiconductor photocatalysts; visible light induced C-C cross-coupling reactions catalyzed by Pd based plasmonic photocatalysts; visible light induced C-C cross-coupling reactions catalyzed by palladium-free photocatalysts; near-infrared light induced C-C cross-coupling reactions.
关键词： Photocatalysis,semiconductor,C-C cross-coupling,localized surface plasmon resonance,Pd
更新于2025-09-23 15:21:21
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Photothermal Effects Induced by Surface Plasmon Resonance at Graphene/Gold Nanointerfaces: A Multiscale Modeling Study
摘要： Surface plasmon resonance (SPR) biosensors have enormous potential in biological recognitions and biomolecular interactions, especially for the real time measurement of disease diagnosis and drug screening. Extensive efforts have been invested to ameliorate the sensing performances, while the photothermal effects, which are induced by the plasmon resonance, have an obvious impact. However, due to the limitations of experimental approaches, the theoretical mechanisms and specific influences of the SPR sensors with photothermal effects are few researched. Here, a multiscale simulation method is developed to investigate the photothermal effects at graphene/gold (Au) nanointerfaces, and to calculate the quantitative contribution of the photothermal effects towards high reliability SPR sensors in order to elucidate their influence on the sensing performances by means of first-principle calculations and molecular dynamics simulations. Our results indicate that the sensitivity and detection accuracy of graphene/Au SPR sensors can be tailored from 0 K to 600 K, due to the tunable dielectric constants of Au and graphene films through temperature variation. By controlling the its material thickness, interfacial combination and lattice strain, an optimized graphene/Au SPR sensor with higher sensitivity, detection accuracy, and reliability to the temperature rising has been achieved. Such multiscale simulation method, which is capable of seeking both the role and the underlying mechanism of the interfacial phenomena, can serve as an excellent guideline for the performance optimization and commercialized application of SPR sensors in the analytical chemistry and biomedical fields.
关键词： graphene/gold nanointerface,photothermal effects,surface plasmon resonance,multiscale simulation method,sensitivity and detection accuracy
更新于2025-09-23 15:21:21
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A sensitive colorimetric probe for detection of 6-thioguanine based on its protective effect on the silver nanoprisms
摘要： In this work a non-aggregated colorimetric probe for detection of chemotherapeutic drug, 6–thioguanine (6-TG), is introduced. It is based on the protective effect of 6-TG on silver nanoprisms (AgNPRs) against the iodide-induced etching reaction. Iodide ions can attack the corners of AgNPRs and etch them, leading to the morphological transition from nanoprisms to nanodiscs. As a consequence, the solution color changes from blue to pink. However, in the presence of 6-TG, due to its protective effect on the corners of AgNPRs, I- ions cannot etch the prisms and the blue color of solution remains unchanged. Using this effect, selective sensor was designed for detection of 6–TG in the range of 2.5-500 μg L-1, with a detection limit of 0.95 μg L-1. Since with varying the concentration of 6-TG in this range, the color variation from pink to blue can be easily observed, the designed sensing scheme can be used as a colorimetric probe. The method was used for analysis of human plasma samples.
关键词： Anti-cancer drugs,Anisotropic nanoparticles,Surface plasmon resonance,Nanomaterials
更新于2025-09-23 15:21:21
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A Strategy for In-Situ Imaging of Cellular Alkaline Phosphatase Activity Using Gold Nanoflower Probe and Localized Surface Plasmon Resonance Technique
摘要： In this work, a simple and ultrasensitive localized surface plasmon resonance (LSPR) method that use Au nanoflowers (AuNFs) as probe was designed for in-situ monitoring of alkaline phosphatase (ALP) activity. The AuNFs was fabricated by hydrogen tetrechloroaurate-induced oxidative disruption of polydopamine-coated Au nanoparticles (AuNPs) and subsequently growth of Au nanopetals on AuNPs. The as-prepared AuNFs showed a much higher LSPR capability and stronger scattering color change than AuNPs. The strategy for in-situ cellular ALP activity detection relied on the deposition of Ag on AuNFs surface, which changed the morphology of AuNFs and led to a tremendous LSPR response and scattering color change. The deposition of Ag shell on AuNFs was related to ALP activity, where ALP catalyzed the hydrolysis of L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate to form L-ascorbic acid (AA), then AA reduced Ag+ to Ag and deposited onto AuNFs. With this concept, the ALP activity could be monitored with a detection limit of 0.03 μU L-1. Meanwhile, the ALP activity of single HepG2 cells and HEK 293 cells was tracked with proposed approach, which indicated the trace expression level of ALP in HEK 293T cell and overexpressed level of ALP in HepG2 cells. After treated with drugs, the cellular ALP activity of HepG2 cells was decreased with the treating time and dose increasing. Therefore, the proposed strategy could be used for tracking the cellular ALP activity, which paved a new avenue for cell studies, and hold great potential for discovering novel ALP-based drugs applications.
关键词： cellular activity,alkaline phosphatase,localized surface plasmon resonance,in-situ imaging,gold nanoflowers
更新于2025-09-23 15:21:21
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Double-sided Polished Ultra-stable and Ultra-sensitive Optical Fiber Sensor
摘要： A double-sided polished photonic crystal fiber (DP-PCF) for surface plasmon resonance(SPR) sensing is designed and analyzed by using the finite element analysis software COMSOL 5.5. The suggested design shows strong sensitivity stability in the low refractive index (RI) region (1.33 ～ 1.39) and ultra-high sensitivity in the high RI region (1.39 ～ 1.43), respectively. The structural parameters of the proposed sensor are studied to analyze the stability and high sensitivity of the fiber sensor. The introduced DP-PCF sensor offers high sensitivity of 32,434 nm/RIU in the RI range of 1.39 ～ 1.43 due to its special double-sided polishing design.
关键词： Photonic crystal fiber,Sensor,Surface plasmon resonance,Surface plasmon polariton
更新于2025-09-23 15:21:01
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Manipulation of the dephasing time by strong coupling between localized and propagating surface plasmon modes
摘要： Strong coupling between two resonance modes leads to the formation of new hybrid modes exhibiting disparate characteristics owing to the reversible exchange of information between different uncoupled modes. Here, we realize the strong coupling between the localized surface plasmon resonance and surface plasmon polariton Bloch wave using multilayer nanostructures. An anticrossing behavior with a splitting energy of 144 meV can be observed from the far-field spectra. More importantly, we investigate the near-field properties in both the frequency and time domains using photoemission electron microscopy. In the frequency domain, the near-field spectra visually demonstrate normal-mode splitting and display the extent of coupling. Importantly, the variation of the dephasing time of the hybrid modes against the detuning is observed directly in the time domain. These findings signify the evolution of the dissipation and the exchange of information in plasmonic strong coupling systems and pave the way to manipulate the dephasing time of plasmon modes, which can benefit many applications of plasmonics.
关键词： Surface plasmon polariton Bloch wave,Strong coupling,Dephasing time,Photoemission electron microscopy,Localized surface plasmon resonance
更新于2025-09-23 15:21:01
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Synthesis of yttrium iron garnet/bismuth quantum dot heterostructures with localized plasmon enhanced magneto-optical performance
摘要： Interactions between light and magnetic matter attracted great attention lately due to their potential applications in nanophotonics, spintronics, and high-accuracy sensing. Here, we grew bismuth quantum dots (Bi–QDs) with strong spin–orbit coupling on a magnetic insulator yttrium iron garnet (YIG) via molecular beam epitaxy. The YIG/Bi–QDs material shows an enhanced magneto-optical Kerr rotation up to 130 % compared with that of a bare YIG film. The Bi–QDs were also introduced onto a lutetium–bismuth co-doped YIG film to form a hybrid system with remarkably enhanced Kerr rotation (from 1626 to 2341 mdeg). Ferromagnetic resonance measurements showed an increased effective magnetization as well as interfacial spin–orbit field in the YIG/Bi–QD heterostructures. Localized plasmons were mapped using electron energy loss spectroscopy with high spatial resolution, revealing enhanced plasmon intensity at both the Bi–QD surface and YIG/Bi–QD interface. Introducing Bi-QDs onto the YIG film enhanced Kerr rotation owing to the attenuated optical reflection and increased effective magnetization. The Bi–QD-enhanced magneto-optical effect enables development of efficient nanoscale light switching, spintronics, and even plasmonic nano-antennas.
关键词： Electron energy loss spectroscopy,Surface plasmon resonance,Bismuth quantum dot,Ferromagnetic resonance,Magneto-optical materials
更新于2025-09-23 15:21:01