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Colloidal Plasmonic Nanostar Antennas with Wide Range Resonance Tunability
摘要： Gold nanostars display exceptional field enhancement properties and tunable resonant modes that can be leveraged to create effective imaging tags, phototherapeutic agents, and hot electron-based photocatalytic platforms. Despite having emerged as the cornerstone among plasmonic nanoparticles with respect to resonant strength and tunability, some well-known limitations have hampered their technological implementation. Herein we tackle these recognized intrinsic weaknesses, which stem from the complex, and thus computationally untreatable, morphology and the limited sample monodispersity, by proposing a novel 6-spike nanostar, which we have computationally studied and synthetically realized, as the epitome of 3D plasmonic nanoantenna with wide range plasmonic tunability. Our concerted computational and experimental effort shows that these nanostars combine the unique advantages of nanostructures fabricated from the top-down and those synthesized from the bottom-up, showcasing a unique plasmonic response that remains largely unaltered in going from the single particle to the ensemble. Furthermore, they display multiple, well-separated, narrow resonances, the most intense of which extends in space much farther than observed before for any plasmonic mode localized around a colloidal nanostructure. Importantly, the unique close correlation between morphology and plasmonic response leads the resonant modes of these particles to be tunable between 600 and 2000 nm, a unique feature that could find relevance in cutting edge technological applications.
关键词： 3D nano-antennas,colloidal nanostars,plasmon tunability,localized surface plasmon resonances,EELS
更新于2025-09-11 14:15:04
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pH-regulated reversible photoluminescence and localized surface plasmon resonances arising from molybdenum oxide quantum dot
摘要： Localized surface plasmon resonances (LSPR) and photoluminescence are important for applications of transition-metal oxides. However, simultaneous control of these optical properties is challenging. Here, a facile strategy is presented that simultaneously tunes photoluminescence and visible LSPR of molybdenum oxide quantum dots (MoOx QDs) by controlling lattice vacancies. Specifically, N-doped MoOx QDs were prepared with a one-pot protocol. The introduction of N in MoOx QDs surfaces via ammonia (NH3) not only trapped oxygen molecules in the process of forming MoOx QDs, but also provided enough free electrons to enable tunable optical properties. Thus, a MoOx QD-based dual-modal fluorescence and LSPR assay was demonstrated via lattice vacancy concentration tuning. Upon introduction of H+ or OH?, pH-reversible tunability of the fluorescence and plasmonic resonance was observed. The dual-mode probe was used to detect extreme acidity in bacterial cells. Overall, tunable LSPR and photoluminescence within one nanostructure via pH-regulation should enable multi-modal signal-outputs for sensing platforms and photoelectric nanodevices.
关键词： Localized surface plasmon resonances,Molybdenum oxide,pH sensor,Dual-modal sensor,Photoluminescence
更新于2025-09-11 14:15:04
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Reversible Photodoping of TiO <sub/>2</sub> Nanoparticles for Photochromic Applications
摘要： Observations on the strong photochromic effect of crystalline TiO2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO2 nanoparticles (NPs) and are dispersed in butanol (8% by mass). Obtained NPs exhibit a dramatic photoresponse to UV light, enabling effective transmittance modulation in a broad wavelength range extending from the visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photoresponse is attributed to hole-scavenging by butanol, TiO2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. The observed optical effect is reversible, and the initial high transmittance state can be restored simply by exposing the NPs to air. The applied NP synthesis route is economic and can be easily scaled for applications such as smart window technologies.
关键词： UV light,TiO2 nanoparticles,localized surface plasmon resonances,transmittance modulation,photochromic
更新于2025-09-04 15:30:14