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Tuning Plasmonic Coupling from Capacitive to Conductive Regimes via Atomic Control of Dielectric Spacing
摘要： The gap length between plasmonic nanoparticles determines the strength of the optical coupling that results in electromagnetic field enhancement for spectroscopic and other applications. Although gap plasmon resonances have been the focus of increasing research interest, experimental observations have primarily been limited to the coupling of spherical nanoparticles that may not provide clear spectral contrast of the optical response as the interaction evolves from capacitive to charge transfer with the gap size decreasing to subnanometer. Here, by taking advantage of the sharp plasmon resonances of colloidal gold nanorods coupled to gold film, we present the spectral evolution of gap plasmon resonance as the particle-film spacing varies from over 30 nm to the touching limit. We find that, the capacitive gap plasmon resonance of the coupled system red shifts and narrows continuously until it vanishes at the quantum tunneling limit, in contrast to the nonlocal and Landau damping effects that are expected to result in relative blue shifting and spectral broadening. When the spacer thickness is further decreased, high order cavity modes appear, and eventually single peak broad resonances that are characteristic of tunneling and direct contact particle-film interaction emerge. The experimental observations show that nanorods are better suited for creating cavity plasmon resonances with high quality factor, and the spectral contrast at the transition provides clarity to develop improved theoretical modeling of optical coupling at subnanometer gap lengths.
关键词： atomic layer deposition,tunneling,plasmon coupling,Particle on metal film,cavity modes,charge transfer,gold nanorods
更新于2025-09-23 15:19:57
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Incorporating graphene quantum dots to enhance the photoactivity of CdSe-sensitized TiO2 nanorods for solar hydrogen production
摘要： This work demonstrated that the incorporation of graphene quantum dots (GQDs) can greatly improve the photoelectrochemical (PEC) efficiency of CdSe-sensitized TiO2 nanorods (TiO2/CdSe), a TiO2-based visible light-responsive photoelectrode paradigm, for solar hydrogen production. For TiO2/CdSe, the accumulated holes at CdSe may induce photocorrosive oxidation to decompose CdSe, deteriorating the long-term stability of photoelectrode and degrading the PEC performance. With the introduction of GQDs, the delocalized holes can further transfer from CdSe to the GQDs, which eases the hole accumulation at the CdSe sites, thus retarding photocorrosion. Compared to the binary TiO2/CdSe photoanode, the ternary TiO2/CdSe/GQDs photoanode displays higher photocurrent and better photostability toward PEC hydrogen production. This superiority can be attributed to vectorial charge transfer and enhanced reaction kinetics provided by the introduction of GQDs. The findings from this work highlight the importance of the introduction of GQDs as a potential solution to the photocorrosion issue of chalcogenide-sensitized semiconductor photoelectrodes.
关键词： photocorrosion,photoelectrochemical efficiency,solar hydrogen production,CdSe-sensitized TiO2 nanorods,graphene quantum dots
更新于2025-09-23 15:19:57
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Photo-Controlled Thermosensitive Electrochemiluminescence Hydrogel for Isocarbophos Detection
摘要： Endowing specificity and controllability with the electrochemiluminescence (ECL) thermosensitive hydrogels is vitally crucial to expand their sensing applications. Herein, a novel photo-controlled thermosensitive electrochemiluminescence hydrogel (PT-ECL hydrogel) sensing platform with sufficient simplicity, specificity and precise controllability, for the first time, is proposed, by the integration of Ru(bpy)3 2+ derivatives (signal reporter), split aptamers (recognition unites), and Au nanorods (AuNRs) (photothermal energy converter) into the poly(N-isopropylacrylamide) (pNIPAM) matrix. In the presence of the model target isocarbophos (ICP), the conjugation of two split-aptamers initiated the ECL-Resonance Energy Transfer (ECL-RET) between the Au nanorods and the Ru(bpy)3 2+ centers. Surprisingly, under the irradiation of near-infrared (NIR) light, the photothermal effect of AuNRs prompted the shrinkage of the hydrogel, resulting in the enhancement of the ECL-RET and further ~7 times signal amplification. Consequently, the PT-ECL hydrogel sensing platform performed well for ICP detection with a low detection limit of 20 pM (S/N=3) and wide linear range from 50 pM to 4 μM, with great stability and repeatability. Obviously, the results showed that AuNRs utilized in this paper served the role as not only the ECL-RET acceptor, but also the photothermal converter to prompt the phase change of the PT-ECL hydrogel precisely and simply controlled by NIR light. Use of the proposed PT-ECL hydrogel detection scheme is a first step toward enabling a newly upgraded highly sensitive, selective hydrogel-based assays and also paving way for the application of smart photothermal reagents.
关键词： split aptamers,Au nanorods,photo-controlled,electrochemiluminescence,isocarbophos detection,thermosensitive hydrogel
更新于2025-09-23 15:19:57
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Cancer cella??specific protein delivery by optoporation with lasera??irradiated gold nanorods
摘要： The delivery of macromolecules into living cells is challenging since in most cases molecules are endocytosed and remain in the endo-lysosomal pathway where they are degraded before reaching their target. Here, a method is presented to selectively improve cell membrane permeability by nanosecond laser irradiation of gold nanorods (GNRs) with visible or near-infrared irradiation in order to deliver proteins across the plasma membrane, avoiding the endo lysosomal pathway. GNRs were labelled with the anti-EGFR (epidermal growth factor receptor) antibody Erbitux to target human ovarian carcinoma cells OVCAR-3. Irradiation with nanosecond laser pulses at wavelengths of 532 nm or 730 nm is used for transient permeabilization of the cell membranes. As a result of the irradiation, the uptake of an anti-Ki-67 antibody was observed in about 50 % of the cells. The results of fluorescence lifetime imaging show that the GNR detached from the membrane after irradiation.
关键词： gold nanorods,optical window,protein delivery,near infrared radiation,nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Fabrication and TCAD validation of ambient air-processed ZnO NRs/CH3NH3PbI3/spiro-OMeTAD solar cells
摘要： This paper reports the fabrication, characterization and simulation of hybrid perovskite solar cells (PSCs) in ambient condition. The proposed PSC structures use a CH3NH3PbI3 hybrid perovskite based active layer sandwiched between a ZnO nanorods (NRs) electron transport layer (ETL) and a spiro-OMeTAD (undoped and doped) hole transport layer (HTL). The ZnO NRs are grown using low-cost solvothermal process at relatively low temperature. The performance of fabricated PSCs are analyzed for both the undoped and doped (with TBP and LiTFSI) spiro-OMeTAD based HTLs. All the solar parameters namely, short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF), power conversion efficiency (PCE) and external quantum efficiency (EQE) are calculated from experimentally measured current density versus voltage (J-V) and wavelength transient characteristics in ambient condition. The maximum PCE of 10.18% is obtained for the doped HTL whereas 9.51% for undoped HTL. The improved performance due to HTL doping is attributed to the enhanced charge transportation of the HTL. The experimental results obtained from the fabricated PSCs are also compared with the SetFosTM TCAD simulation data using drift-diffusion model. The simulated results are observed to be well matched to the experimental data.
关键词： Perovskite,ZnO nanorods,solvothermal method,power conversion efficiency,solar cells
更新于2025-09-23 15:19:57
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Influence of the Fifth-Order Nonlinearity of Gold Nanorods on the Performance of Random Lasers
摘要： We present the first experimental evidence for the influence of the fifth-order nonlinearity on the characteristics of Random Lasers with plasmonic nanoparticles as scatterers. The experiments were performed with gold nanorods suspended in an ethanolic solution of Rhodamine 6G, pumped by a picosecond laser. It is shown that by varying the nanorods aspect-ratio, it is possible to control the cooperative influence of both transverse and longitudinal localized surface plasmons on the fifth-order nonlinear light scattering, a phenomenon that allows to manage the optical feedback causing significant changes in the threshold intensity and emission power of Random Lasers.
关键词： fifth-order nonlinearity,gold nanorods,Random Lasers,optical feedback,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Dual-Color Plasmonic Nanosensor for Radiation Dosimetry
摘要： Radiation dosimeters are critical for accurately assessing the levels of radiation exposure of tumor sites and surrounding tissues and for optimizing therapeutic interventions as well as for monitoring environmental exposure. To fill the need for a simple, user-friendly and inexpensive dosimeter, we designed an innovative colorimetric nanosensor-based assay for detecting ionizing radiation. We show that hydroxyl radicals generated by ionizing radiation can be used to etch gold nanorods (AuNRs) and silver nanoprisms (AgNPRs), yielding reproducible color changes for radiation dose detection in the range of 50-2000 Rad, broad enough to cover doses used in hyperfractionated, conventional, and hypofractionated radiotherapy. This range of doses detected by this assay correlates with radiation induced DNA damage response in mammalian cells. Furthermore, this AuNR- and AgNPR-based sensing platform has been established in a paper format that can be readily adopted for a wide range of applications and translation.
关键词： Radiation dosimetry,gold nanorods,silver nanoprisms,dual-color nanosensor,colorimetric detection
更新于2025-09-23 15:19:57
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Spatio-Spectral Characterization of Multipolar Plasmonic Modes of Au Nanorods via Tip-Enhanced Raman Scattering
摘要： Tip-enhanced Raman (TER) spectral images of 4-thiobenzonitrile-coated Au nanorods map the spatial profiles and trace the resonances of dipolar and multipolar plasmonic modes that are characteristic of the imaged particles. For any particular rod, we observe sequential transitions between high-order modes at low frequency shifts and lower-order modes at higher frequencies. We also notice that higher order modes (up to m=4) are generally observed for long rods as compared to their shorter analogues, where longitudinal dipolar resonances (m=1) are observable. In effect, this work adds a new dimension to local optical field mapping via TERS, which we have previously explored. Not only can the magnitudes, vector components, local/non-local characters of local optical fields be imaged through molecular TERS, but spatially varying local optical resonances are direct observables.
关键词： Tip-Enhanced Raman,Nano-Spectroscopy,Local Optical Fields,Gold Nanorods,Multipolar Plasmons
更新于2025-09-23 15:19:57
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[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia, Romania (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - Substrate Effect on the Morphology and Optical Properties of ZnO Nanorods Layers Grown by Microwave-Assisted Hydrothermal Method
摘要： The substrate effect on the morphology and optical properties of zinc oxide nanorods synthesized by microwave-assisted hydrothermal method have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-VIS-NIR optical absorption and reflecting spectroscopy. The band gap energy of the investigated samples was calculated from absorbance spectra in the (200-1100) nm wavelengths range.
关键词： optical properties,ZnO nanorods,band gap energy,microwave-assisted hydrothermal synthesis,morphology
更新于2025-09-23 15:19:57
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Localized Nanoscale Heating Leads to Ultrafast Hydrogel Volume-Phase Transition
摘要： The rate of the volume-phase transition for stimuli-responsive hydrogel particles ranging in size from millimeters to nanometers is limited by the rate of water transport, which is proportional to the surface area of the particle. Here, we hypothesized that the rate of volume-phase transition could be accelerated if the stimulus is geometrically controlled from the inside-out, thus facilitating outward water ejection. To test this concept, we applied transient absorption spectroscopy, laser temperature-jump spectroscopy and finite-element analysis modeling to characterize the dynamics of the volume-phase transition of hydrogel particles with a gold nanorod core. Our results demonstrate that nanoscale heating of the hydrogel particle core led to an ultrafast, 60 ns particle collapse, which is 2-3 orders of magnitude faster than the response generated from conventional heating. This is the fastest recorded response time of a hydrogel material, thus opening potential applications for such stimuli-responsive materials.
关键词： infrared spectroscopy,dynamic light scattering,nanorods,volume-phase transition,hydrogel,transient absorption
更新于2025-09-23 15:19:57