Metal Nanoshells Research Articles

A Study of Degenerate Four‐Wave Mixing and Phase Conjugation in Metallic Nanohybrids

AbstractA theory of degenerate four‐wave mixing (DFWM) and phase conjugation is developed for metallic nanohybrids, which consist of an ensemble of interacting metallic nanoshells and noninteracting quantum dots (QDs). It is considered that three incident waves are applied to the metallic nanohybrid, and they produce a fourth output mixed wave. These waves induce dipoles in metallic nanoshells, generating surface plasmon polaritons, and interact with each other via the dipole–dipole interactions (DDI). In DFWM, the input and output waves travel in opposite directions, and this retroreflective nature is responsible for the phenomenon of phase conjugation. The analytical expressions for the input transmitted and output reflected wave intensities are calculated in the presence of the surface plasmon polaritons (SPPs) and the DDI polaritons. It is demonstrated that the phase conjugation, the phase coherent phenomena, and the intensities of both input transmitted and output reflected waves are enhanced due to SPPs and DDI polaritons. These findings indicate that the nanohybrid acts as a phase conjugate device and a phase coherent optical amplifier, which can be applied to fabricate optical nanoamplifiers, phase conjugate mirrors, and nanosensors by measuring the intensity of the output reflected wave.

Third- and fifth-order nonlinearities in quantum dot hybrid systems: Influence of graphene and metal nanoparticles

This work examines the third-order and fifth-order nonlinear susceptibilities in a hybrid system including a semiconductor quantum dot, metallic nanoshell, and graphene nanodisk. The research uses the density matrix method to examine the dipole–dipole interaction that occurs due to the applied field. It assumes that there is an increase in the strength of a continuous-wave electromagnetic field inside the quantum dot. The inclusion of the graphene nanodisk greatly amplifies the nonlinear optical reaction of the quantum dot in this combined system, which is governed by the dipole–dipole interaction. The findings indicate a notable disparity in the nonlinear optical reaction of the semiconductor quantum dot when the parameters are modified. The possible applications of this concept include optical sensors, photonic devices, quantum computing, medical imaging, energy harvesting, and high-density data storage. Additionally, it has the potential to progress terahertz technology and simplify the development of new materials with customized optical properties. The substantial rise in nonlinearities inside the hybrid system presents prospects for advancements in diverse technological and scientific domains.

Control of dual-channel optical bistability in a carbon nanotube nanoresonator coupled with a metallic nanoshell

Control of dual-channel optical bistability in a carbon nanotube nanoresonator coupled with a metallic nanoshell

Opto-Thermal Properties of some Composite Metallic Nanoshells for their Thermoplasmonic Applications

Opto-Thermal Properties of some Composite Metallic Nanoshells for their Thermoplasmonic Applications

Modulating Kerr nonlinearity and optical bistability in a monolayer graphene nanoribbon nanoresonator coupled to a metallic nanoshell

A scheme for modulating Kerr nonlinearity and optical bistability (OB) based on a monolayer graphene nanoribbon nanoresonator (NR) and a metallic nanoshell (MNS) is proposed. The MNS is made of an Au nanoshell and a dielectric core. Here, we not only demonstrate that the spectrum of the Kerr coefficient can switch from a four-peaked structure to a two-peaked structure by increasing the shell thickness of the MNS, but also plot bistability phase diagrams in the system’s parameter subspace, revealing that the bistable effect can be controlled via zero-channel, one-channel or two-channels by only changing the shell thickness in a strong exciton-phonon coupling regime. Additionally, the calculated results also show that the material of the core of MNS plays an essential role in tuning OB when the shell thickness is fixed. The findings pave a new way for developing optical Kerr switches and high-flexible bistable nanodevices.

Role of surface damping on hybrid modes and electric field enhancement distribution of ultrathin metal-coated dielectric microspheres illuminated by non-resonant light

Herein, we report a theoretical investigation on the characteristic parameters of hybrid plasmonic–photonic modes (or simply hybrid modes) and electric field enhancement (EFE) distribution of ultrathin Au- and Ag-coated dielectric microspheres illuminated by non-resonant light obtained with and without consideration of the size-dependent damping (SDD) or surface damping in ultrathin metal nanoshells. From the obtained scattering and absorption spectra, the role of SDD on characteristic parameters such as wavelength locations, full width at half maximum, and EFE of the hybrid modes is investigated for the first time, to our knowledge. In addition, the effect of metal shell thickness (t) on the hybrid modes is studied. The EFE distribution inside/outside the ultrathin metal-coated dielectric microspheres illuminated by non-resonant light is investigated. More importantly, the sensitivity of the EFE distribution of bare and metal-coated microspheres is explored by slightly varying the resonant and non-resonant wavelengths.

Optical bistability in a heterodimer composed of a quantum dot and a metallic nanoshell.

We theoretically explore the conditions for generating optical bistability (OB) in a heterodimer comprised of a semiconductor quantum dot (SQD) and a metallic nanoshell (MNS). The MNS is made of a metallic nanosphere as a core and a dielectric material as a shell. For the specific hybrid system considered, the bistable effect appears only if the frequency of the pump field is equal to (or slightly less than) the exciton frequency for a proper shell thickness. Bistability phase diagrams, when plotted, show that the dipole-induced bistable region can be greatly broadened by changing the shell thickness of the MNS in a strong exciton-plasmon coupling regime. In particular, we demonstrate that the multipole polarization not only narrows the bistable zone but also enlarges the corresponding thresholds for a given intermediate scaled pumping intensity. On the other hand, when the SQD couples strongly with the MNS, the multipole polarization can also significantly broaden the bistable region and induce a great suppression of the FWM (four-wave mixing) signal for a fixed shell thickness. These interesting findings offer a fresh understanding of the bistability conditions in an SQD/MNS heterodimer, and may be useful in the fabrication of high-performance and low-threshold optical bistable nanodevices.

DNA-Guided Extracellular-Vesicle Metallization with High Catalytic Activity for Accurate Diagnosis of Pulmonary Nodules.

Sensitive and specific analysis of extracellular vesicles (EVs) offers a promising minimally invasive way to identify malignant pulmonary nodules from benign lesions. However, accurate analysis of EVs is subject to free target proteins in blood samples, which compromises the clinical diagnosis value of EVs. Here a DNA-guided extracellular-vesicle metallization (DEVM) strategy is described for ultrasensitive and specific analysis of EV protein biomarkers and classification of pulmonary nodules. The facile DEVM process mainly includes the incorporation of DNA labeled with cholesterol and thiol groups into EV membranes and subsequent deposition of Au3+ and Pt4+ to allow the DNA-functionalized EVs to be encapsulated with AuPt nanoshells. It is found that the synthesized AuPt-metallized EVs possess extrinsic peroxidase-like activity. Utilizing the feature of the catalytic metal nanoshells just growth on the EV membranes, the DEVM method enables multiparametric recognition of target proteins and EV membranes and can produce an amplified colorimetric signal, avoiding the interference of free proteins. By profiling four surface proteins of EVs from 48 patients with pulmonary nodules, the highest area under the receiver operating characteristic curve (0.9983) is obtained. Therefore, this work provides a feasible EVs analysis tool for accurate pulmonary nodules management.

Linear optical response of a quantum dot ‒ metal nanoshell hybrid system

Linear optical response of a quantum dot ‒ metal nanoshell hybrid system

Analytical results for enhancement factor (EF) of surface enhanced Raman spectroscopy (SERS) for two metallic spheres and nano-shells

Interactions between symmetric two metallic spheres and an electromagnetic (EM) field polarized in the symmetric axis are described. Spherical symmetries of the present systems are exploited by the use of bi-spherical coordinates. Boundary conditions are applied, which assume a very large negative value for the dielectric constant of special metals. The EM field in small gaps (in hotspots) is amplified by many orders of magnitude relative to the external field. Analytical results for the maximal enhancement factor in surface enhanced Raman spectroscopy for two metallic spheres and two nano-shells are obtained as a function of various parameters. The calculations are based on potentials derived by using an electrostatic model, which is valid for very small particles.

Drastic performance enhancement of photoluminescence and water electrolysis by local-magnetic-field-assisted LSPR of Ag NPs and NCs

A novel method is presented for drastically improving the local surface plasma resonance (LSPR) effect of noble metal nanoparticles (NPs) and nanoclusters (NCs). This is realized by magnetizing particles comprising a ferrimagnetic core and a noble metal nanoshell. In this study, we prepared Fe3O4 @SiO2 @Ag composite particles. Ag NPs and NCs had the size of 10–15 nm and 2–3 nm, respectively. The photoluminescence (PL) intensities of ZnO and YAG:Ce substrates coated with the magnetic composite particles increased by 160 % and 50 %, respectively, after magnetization under a magnetic field of 18 mT compared to the unmagnetized state. The activity of Ni-foam-based-Fe3O4 @SiO2 @Ag working electrode for water electrolysis was also significantly improved after magnetization. The increasing rate of current density after magnetization was 226 mA∙cm−2/0.1 V, which is higher than 158 mA∙cm−2/0.1 V before the magnetization. The mechanism for drastic performance enhancement of PL and water electrolysis postulates that after magnetization, the remanence of the ferrimagnetic Fe3O4 core provides a local magnetic field to strengthen the local electric field in the confined area of Ag NPs/NCs. It was confirmed by the higher intensity of peaks in Raman spectroscopy and contributed to the enhancement of LSPR effect. This efficient and practical approach to magnetization-induced LSPR improvement has potential application prospects in LSPR-related fields.

Fabrication of Pd–Ni/Au nanoshelled microsphere array for electrocatalytic oxidation of methanol

Pd–Ni/Au nanoshelled microsphere arrays with different Pd–Ni atomic ratios were successfully synthesized using the etched monolayer colloidal spheres as templates. Morphology and composition characterizations indicated that the prepared products consisted of polystyrene cores of Au and Pd–Ni metallic nanoshells with an overall diameter of 450 nm. Electrochemical measurements in an alkaline solution showed that the Pd–Ni/Au catalyst with Pd:Ni = 4:1 atomic ratio demonstrated an optimal catalytic activity with the peak current of 59.4 mA[Formula: see text], the lower oxidation peak potential and the higher stability. These results could be ascribed to the enhanced surface area which increased the number of electrocatalytic active sites, and the electronic interaction between Pd and Ni. This work provides new opportunities for the rational design of microsphere array catalysts for enhancing the catalytic performance in fuel cells.

Photon amplification and cavity-polariton-like generation in metallic nanoshells localized in optical cavity.

In this paper, I provide nanoshell as a new candidate to achieve the lasing and cavity-polariton-like. Owing to the energy levels in hybridized plasmon modes of nanoshell, I combine the two-level nature of dark and bright plasmon modes of nanoshell with plasmon enhancement of optical second-order nonlinear in metal surface to achieve the lasing of photon, especially under the condition of no population inversion. This provide a new idea to realize nanolaser. Furthermore, using the dipole-dipole interaction between naoshells, the one dimensional array of nanoshells can form new lattice plasmon polaritons similar to exciton-polariton in optical microcavity. Because the nanoshells are much easier to control compared with atoms, the nanoshells arrays (1D and 2D) are good platforms to mimic atomic arrays interacting with cavity photons. This has some potential value in quantum optics of plasmon.

The Effect of the Core on the Absorption in a Hybrid Semiconductor Quantum Dot—Metal Nanoshell System

We examine the optical absorption in a hybrid structure composed of a metal nanoshell and a semiconductor quantum dot, while interacting with a linearly polarized probe electromagnetic field. First, we derive the equations of motion, in the rotating wave approximation. Then we procced to the derivation of analytical expressions for the linear susceptibility of the metal nanoshell and the semiconductor quantum dot. The imaginary part of the susceptibility expresses the absorption coefficient. We find that by properly engineering the thickness of the metal nanoshell, the material of the dielectric core and the interparticle distance, we may achieve an optimum response. We identify the emergence of two distinct types of hybrid exciton states. One of them emerges in the strong exciton–plasmon coupling regime for low values of the dielectric constant and the radius of the dielectric core. This type of hybrid exciton exhibits an amplified gain without population inversion and a quenched absorption resonance accompanied by a suppressed exciton lifetime. The second type of hybrid exciton emerges in the weak exciton–plasmon coupling regime and presents the opposite spectral characteristics. Here, the exciton lifetime presents a substantial increase, especially for small interparticle distances, in which case the semiconductor quantum dot and the metal nanoshell are strongly coupled with one another.

Strong coupling with directional scattering features of metal nanoshells with monolayer WS2 heterostructures

Realizing and manipulating strong light–matter coupling in 2D monolayer semiconductors are of the utmost importance in the development of photonic devices. Hollow nanostructures of noble metals are particularly interesting because of their stronger local electromagnetic field compared with solid nanoparticles, which facilitate the strong coupling of single metal nanostructures. Here, the tunable single nanocavity plasmon–exciton coupling was demonstrated at room temperature in hybrid systems consisting of Ag@Au hollow nanocubes (HNCs) and monolayer WS2 underneath, where a large vacuum Rabi splitting of 131.3 meV was observed. Mode splitting can be clearly observed from the dark-field scattering spectrum of the single hybrid nanocavity, which is ascribed to the strong coupling between the nanocavity mode and the excitonic mode. Then, we used the finite difference time domain method to simulate these hybrid systems. By changing the thickness of the shell of the Ag@Au HNC, we can tune the surface plasmon resonance peak position of HNCs to match the exciton energy of the monolayer WS2. The strong couplings were realized via the calculated scattering spectra. The calculated results were consistent with the experimental results. Furthermore, the mode volume of different nanostructures was discussed, and the mode volume of HNCs is smaller than other solid ones at the same plasmonic resonance wavelength, which also indicates that its ability to restrict an electromagnetic field is stronger. This study provides an ideal platform for the strong coupling of a single nanocavity at room temperature and has broad application prospects in the field of single-photon devices.

Application of Nanoparticle in the Veterinary Medicine

Nanotechnology is a modern and developed technology, which have great importance in many fields of medicine (diagnosis and treatment). Also, it used to prevent and solve many problems related to animal production and health. The Nanosystems are including metallic nanoparticles, liposomes, polymeric Nanospheres, polymeric micelles, carbon nanotubes, functionalized fullerenes, polymer-coated Nanocrystals, dendrimers and Nanoshells. Our review showed a details classification of nanoparticles and their uses. Nanoparticles have several features depended on the size, colossal surface. The development of antibiotics nanoparticle is very important and has an excellent impact in treating bacterial infections wherever the antibiotics nanoparticle gives high therapeutic effect without negative side effects. Our review showed some aspects of the nanoparticles' classification and their uses in general form and veterinary medicine, focusing the light on nanoparticle applications in the nutrient, Biocides, meat and egg quality, milk, animal treatment diseases, and reproduction the animals.

Plasmonic hybridization in the presence of topological insulators

The hybridization model for the coupled plasmons of a metallic nanoshell is generalized to the case with the presence of topological insulator materials via the application of axion electrodynamics. A new approach has to be adopted in the Lagrangian formulation of the coupling dynamics between the surface and cavity plasmons to account for the axion-induced charges on the boundary surfaces. It is found that, as observed previously from numerical studies in the literature, the hybridization model predicts that a topological magneto-electric effect will lead to red shifts on both the coupled bonding and anti-bonding modes–more significant for the higher-order bonding modes with the increase of the axion coupling parameter.

Facile Synthesis of Conductive Flexible Composite Sn@Ag Microspheres and their Application in Anisotropic Conductive Films

AbstractComposite microspheres with noble metal nanoshells are advantageous in flexible circuit connections, flip chips, and chemical sensors. It is difficult for Polystyrene microspheres to cover a complete Ag layer, and hard metal microspheres have no deformability. These two reasons have contributed to this research. This report demonstrates a facile synthesis route that chemically deposits an Ag layer on the surface of 30 µm Sn microspheres to form a composite Sn@Ag double‐layer structure, which is suitable for anisotropic conductive films (ACFs) with linewidths greater than 100 µm. Scanning electron microscope analysis reveals that the surface Ag coating thickness can be controlled within the range of 737 nm–5.62 µm by varying the amount of Ag source applied, and trace free Ag particles are produced during the preparation process. An anisotropic conductive adhesive film is successfully fabricated and hot‐pressed after the film‐on‐film flexible circuit board. The microspheres form an ACF single‐layer structure after hot pressing. Hot pressing in the range of 10–20 MPa can ensure deformation and avoid Ag shell cracking, and the deformation is determined when Sn@Ag is in contact with the circuit surfaces at both ends. This approach provides a potential method of preparing low‐cost and high‐performance ACFs.

Surface plasmon resonance in the presence of topological insulators

The plasmonic resonance of the free electrons at a metal-topological insulator interface is studied with the application of axion electrodynamics. The additional red-shift due to the axion field previously observed in the literature is accounted for by a mechanical model similar to that used in the hybridization model for coupled plasmonic resonances in metallic nanoshells. Such model sheds light on the origin of the red-shift being caused by the decrease in interaction potential energy for the free electron fluid due to the axion-induced charges at the interface of the metal and the topological insulator.

Excitation of Localized Plasmons in Metal Nanoshell and Nanotube with Dielectric Cores

Excitation of Localized Plasmons in Metal Nanoshell and Nanotube with Dielectric Cores