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Structure characterization and photoluminescence of sol-gel synthesized Ag-Dy-codoped silica phosphor
摘要： Bulk samples of single Ag-, Dy-doped and Ag-Dy-codoped silica matrices were synthesized using the sol-gel processing. These matrices were characterized using X-ray di?ractometry, ultraviolet-visible-near infrared (UV-VIS-NIR), Fourier transform infrared, photoluminescence (PL) excitation and emission spectroscopic techniques. High resolution transmission electron microscope con?rmed the presence of ?ne spherical Ag nanoparticles (NPs), whose average size is approximately 10–15 nm, in the Ag-doped and Ag-Dy-codoped silica matrices. UV-VIS-NIR spectra revealed absorption peaks due to Dy3+ active centers in addition to the surface plasmon resonance bands of Ag NPs centered at 410 and 452 nm in these matrices, respectively. UV-excited PL of the materials was studied and compared. Near-white light emission, which was assessed by the calculated CIE chromaticity coordinates, could be observed under UV excitation at 365 nm in the Ag-Dy-codoped silica matrix. This white light was realized by appropriate combination of prominent yellow and blue emissions. Electron spin resonance spectra revealed paramagnetic spin states for Ag which can be attributed to the quantum size e?ect of very ?ne Ag NPs dispersed in the silica network. The obtained results indicate that the Ag-Dy-codoped silica phosphor could be a promising candidate for application as white light emitting phosphor for UV LED chips.
关键词： Sol-gel,TEM,Surface plasmon resonance,Phosphors,White LED,Optical band gap
更新于2025-09-10 09:29:36
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Plasma Based Synthesis of Nanomaterials for Development of Plasmon Enhanced Infrared Responsive Optoelectronic Device
摘要： We report plasma based fabrication of an optoelectronic device with plasmon enhanced infrared sensitivity realized by integrating plasmonic gold nanoparticles (Au NPs) with an organic semiconductor matrix. A blend of plasma polymerized aniline (PPA)-Rubrene, prepared by a novel plasma based method acts as the semiconductor matrix for charge transport in the device geometry. Significantly improved photovoltaic property of the device with an open circuit voltage (VOC) of 1.08 V is obtained with the addition of Au NPs in the device. We experimentally demonstrate very efficient plasmon generated charge transfer between Au NPs and PPA-Rubrene system leading to significant enhancement of infrared responsivity of 2200% at the plasmon absorption band of Au. This study demonstrates how plasma based processes can be utilized to prepare plasmonic nano-materials and also to synthesize organic semiconductor materials suitable for development of plasmonic charge generating devices responsive to infrared region of the electromagnetic spectrum.
关键词： Infrared responsive,Plasma process,Optoelectronic device,Surface plasmon
更新于2025-09-10 09:29:36
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Plasmon-tunable Au@Ag core-shell spiky nanoparticles for surface-enhanced Raman scattering
摘要： A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nanoparticles (NPs) to tailor the localized surface plasmon resonance (LSPR) properties. The gradual assembly of small Au nanocrystals allows the size of spiky Au NPs to be modulated from tens to several hundreds of nanometers by tuning the concentration of initial Au seeds and Au source; and the thickness of the Ag shell can be adjusted with stepwise reduction of Ag(I) ions. The LSPR bands of such spiky Au@Ag core-shell NPs resemble those of pure spiky Au NP cores of similar sizes in near-infrared region, and increasing the Ag shell thickness results in a blue shift and broadening of the LSPR band in the near-infrared region. Additionally, the spiky Au@Ag core-shell NPs exhibit improved surface-enhanced Raman scattering (SERS) activity as compared to the bare spiky Au NPs and spherical Ag@Au NPs. This work has offered a facile route to synthesize plasmonic metal NPs with LSPR band in 650 to 800 nm that show strong enhancement of localized electromagnetic field, which provides an effective SERS substrate for SERS imaging and detection in biological fluids and tissues.
关键词： localized surface plasmon resonance,gold,silver,surface-enhanced Raman spectroscopy
更新于2025-09-10 09:29:36
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Plasmon-enhanced upconversion photoluminescence: mechanism and application
摘要： The enhanced local electromagnetic field (EM) excited on the noble metallic nanostructure exhibits potential application in various areas, particularly in surface-enhanced spectroscopy (SES). Resonant coupling of SPs to luminous centers can strongly moderate the emission spectra properties, including the angular distribution, the intensity, the speed of radiative decay, and even the spectrum radiation polarization, or so-called plasmon-enhanced fluorescence (PEF). Due to the low efficiency of emission and small absorption section of rare earth ions, plasmon-enhanced upconversion photoluminescence(PUCPL) has attracted increasing attention recently. In this review, we focus on recent advanced reports on PUCPL. First, the mechanism of the conventional upconversion process and related reports will be introduced. We will then demonstrate that the introduction of plasmonic nanostructure, including nonperiodic and periodic metallic nanostructures, has a critical effect on upconversion nanoparticles(UCNPs). The recent advances in plasmon-enhanced fluorescence with metallic tip configuration are also noted. Finally, the recent applications of PUCPL are introduced. As a result, the combination of a rare-earth luminescent center with plasmonic nanostructure can largely expand the application of upconversion materials.
关键词： surface-enhanced spectroscopy,mechanism,plasmonic nanostructure,Plasmon-enhanced upconversion photoluminescence,application,rare earth ions
更新于2025-09-10 09:29:36
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Surface plasmon resonance of gold nanoparticles as a colorimetric sensor for indirect detection of Cefixime
摘要： This study reports a colorimetric sensor with excellent sensitivity to detect Cefixime base on gold nanoparticles. Cefixime is an antibiotic which has a wide range of applications in medicine. Cefixime did not change the surface plasmon resonance bond in gold nanoparticles solution; therefore, there was no change in the color solution of gold nanoparticles. The presence of Alizarin Red S in the system was necessary for the degradation of Cefixime, resulting in the aggregation of gold nanoparticles and a color change from red to blue. As a result of aggregation, the localized surface plasmon resonance band of gold nanoparticles decreased to around 525 nm and a new red-shifted band at 640 nm appeared which increases gradually as the function of Cefixime concentration. A unique detection limit (2.5 ng mL-1) was achieved for Cefixime in comparison with other colorimetric methods. Relative standard deviations (RSD) for 40.0 and 140.0 ng mL-1 of Cefixime were 2.6 and 1.8% for intra–day respectively. A possible mechanism was discussed for the surface plasmon resonance changes of AuNPs in the presence of Cefixime. The proposed method was applied to detect Cefixime in pharmaceutical samples with satisfactory results. This system is low-cost and is highly sensitive with no need for any preconcentration steps or using any expensive or sophisticated instrumentation.
关键词： gold nanoparticle,Cefixime,spectrometric method,surface plasmon resonance
更新于2025-09-10 09:29:36
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On electromagnetic surface waves supported by an isotropic chiral material
摘要： Electromagnetic surface waves supported by an isotropic chiral material were investigated via the associated canonical boundary-value problem. Specifically, two scenarios were considered: surface waves guided by the planar interface of an isotropic chiral material and (a) an isotropic dielectric (or plasmonic) material and (b) a uniaxial dielectric (or plasmonic) material. Both plasmonic and non-plasmonic achiral partnering materials were investigated. In scenario (a) surface waves akin to surface-plasmon-polariton (SPP) waves were excited, while in scenario (b) surface waves akin to Dyakonov waves and akin to SPP waves were excited. For numerical studies, an isotropic chiral material capable of simultaneously supporting attenuation and amplification of plane waves, depending upon circular polarization state, was used. The amplitude of the SPP-like waves could be either amplified or attenuated, depending upon the relative permittivity of the isotropic plasmonic partnering material for scenario (a), or depending upon the direction of propagation relative to the optic axis of the uniaxial plasmonic partnering material for scenario (b).
关键词： Dyakonov wave,Surface plasmon polariton wave,Isotropic chiral material
更新于2025-09-10 09:29:36
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Single-layer graphene-coated gold chip for electrochemical surface plasmon resonance study
摘要： Surface plasmon resonance (SPR) employs a gold (Au) thin film (ca. 50 nm in thickness) chip to generate a surface plasmonic wave (SPW) for in situ monitoring of the interface/surface, which makes it intrinsically compatible with electrochemistry for combined electrochemical surface plasmon resonance (EC-SPR) investigations. However, conventional SPR Au chips suffers from a high background signal, narrow electrochemical window, and limited electrochemical stability. Presented in this work is a novel SPR chip composed of the Au/long-chain alkane thiol self-assembled monolayer/single-layer graphene (Au/SAM/G) sandwich architecture to address these problems. On this chip, the single-layer graphene serves as a working electrode for electrochemical measurement, and the underlying Au film serves as the SPW support for SPR monitoring; the sandwiched thiol monolayer enables the electrical separation of the graphene and Au film to protect the Au film from electrochemical polarization. Our experiment indicates that the electrochemical window of such a chip extends beyond the hydrogen/oxygen evolution reaction potential on Au with significantly improved electrochemical stability and suppressed background signal. Moreover, its intrinsic SPR sensitivity is completely reserved even compared to that of the conventional SPR Au chip. This Au/SAM/G chip may offer a valuable solution to the EC-SPR investigations in harsh conditions.
关键词： Electrochemical surface plasmon resonance,Single-layer graphene,Electrochemical window,Chip
更新于2025-09-10 09:29:36
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Tunable optical nonlinearity of Au-TiO2 nanocomposites
摘要： The present work is focused on the correlation studies of Fermi energy level and optical nonlinearity of Au-TiO2 nanocomposites. The Fermi energy and optical nonlinearity are found to be nearly proportionally related with respect to concentration of Au. The observed shift in Fermi level with increasing concentration of Au is due to charge transfer between TiO2 and Au in the presence of ultraviolet light irradiation during the formation of Au-TiO2 nanocomposites. The estimated third order optical nonlinearity was found to increase from 3.80×10-6 to 9.69×10-6 esu with increase in Au concentrations from 0 to 1.0×10-2 M. This observed increment in nonlinearity is due to the enhancement of local electric field created by excitation of surface plasmon resonance that affects the Fermi energy level or work function.
关键词： Work function,Z-scan technique,Nanocomposites,Surface plasmon resonance,Optical nonlinearity
更新于2025-09-10 09:29:36
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Surface enhanced perfect absorption in metamaterials with periodic dielectric nanostrips on silver film
摘要： Integrated dielectric metamaterials with plasmonic structures can cause drastic optical resonances and strengthen the capacity of light absorption. Here, we describe the optical properties of silicon nanoarrays on a thin silver film for extreme light confinement at subwavelength nanoscales. We attain the nearly total absorption in silicon nanostrips, which support magnetic quadruple Mie-type resonances in the visible regions. The Mie resonant field of the dielectric nanostrip engages the screening response of the silver film, resulting in plasmon resonance configuration and thus achieving perfect light absorption in the dielectric nanostrip. Moreover, we can attain similar results in other nanostructures, such as silicon cylinder and rhombus column arrays. Because it can sustain hybridized plasmon modes and magnetic modes, the combined system will benefit the application of solar energy accumulation.
关键词： surface plasmon polaritons,plasmonic structures,dielectric metamaterials,Mie resonances,perfect absorption
更新于2025-09-10 09:29:36
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Lectins at Interfaces—An Atomic Force Microscopy and Multi-Parameter-Surface Plasmon Resonance Study
摘要： Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary.
关键词： lectin,gold,adsorption,bovine serum albumin,polystyrene,surface plasmon resonance spectroscopy,cellulose thin film
更新于2025-09-10 09:29:36