Nonlocality-driven supercontinuum white light generation in plasmonic nanostructures.
Ontology highlight
ABSTRACT:
SUBMITTER: Krasavin AV
PROVIDER: S-EPMC4865813 | biostudies-other | 2016
REPOSITORIES: biostudies-other
Similar Datasets
Project description:In the surface-enhanced fluorescence (SEF) process, it is well known that the plasmonic nanostructure can enhance the light emission of fluorescent emitters. With the help of atomic force microscopy, a hybrid system consisting of a fluorescent nanodiamond and a gold nanoparticle was assembled step-by-step for in situ optical measurements. We demonstrate that fluorescent emitters can also enhance the light emission from gold nanoparticles which is judged through the intrinsic anti-Stokes emission owing to the nanostructures. The light emission intensity, spectral shape, and lifetime of the hybrid system were dependent on the coupling configuration. The interaction between gold nanoparticles and fluorescent emitter was modelled based on the concept of a quantised optical cavity by considering the nanodiamond and the nanoparticle as a two-level energy system and a nanoresonator, respectively. The theoretical calculations reveal that the dielectric antenna effect can enhance the local field felt by the nanoparticle, which contributes more to the light emission enhancement of the nanoparticles rather than the plasmonic coupling effect. The findings reveal that the SEF is a mutually enhancing process. This suggests the hybrid system should be considered as an entity to analyse and optimise surface-enhanced spectroscopy.
| S-EPMC5826936 | biostudies-literature
Project description:Supercontinuum (SC) light sources hold versatile applications in many fields ranging from imaging microscopic structural dynamics to achieving frequency comb metrology. Although such broadband light sources are readily accessible in the visible and near infrared regime, the ultraviolet (UV) extension of SC spectrum is still challenging. Here, we demonstrate that the joint contribution of strong field ionization and quantum resonance leads to the unexpected UV continuum radiation spanning the 100 nm bandwidth in molecular nitrogen ions. Quantum coherences in a bunch of ionic levels are found to be created by dynamic Stark-assisted multiphoton resonances following tunneling ionization. We show that the dynamical evolution of the coherence-enhanced polarization wave gives rise to laser-assisted continuum emission inside the laser field and free-induction decay after the laser field, which jointly contribute to the SC generation together with fifth harmonics. As proof of principle, we also show the application of the SC radiation in the absorption spectroscopy. This work offers an alternative scheme for constructing exotic SC sources, and opens up the territory of ionic quantum optics in the strong-field regime.
| S-EPMC9283425 | biostudies-literature
Project description:Structural colour generation by nanoscale plasmonic structures is of major interest for non-bleaching colour printing, anti-counterfeit measures and decoration applications. We explore the physics of a two-metal plasmonic nanostructure consisting of metallic nanodiscs separated from a metallic back-reflector by a uniform thin polymer film and investigate the potential for vibrant structural colour in reflection. We demonstrate that light trapping within the nanostructures is the primary mechanism for colour generation. The use of planar back-reflector and polymer layers allows for less complex fabrication requirements and robust structures, but most significantly allows for the easy incorporation of two different metals for the back-reflector and the nanodiscs. The simplicity of the structure is also suitable for scalability. Combinations of gold, silver, aluminium and copper are considered, with wide colour gamuts observed as a function of the polymer layer thickness. The structural colours are also shown to be insensitive to the viewing angle. Structures of copper nanodiscs with an aluminium back-reflector produce the widest colour gamut.
| S-EPMC6669635 | biostudies-literature
Project description:Light absorption efficiency of heterogeneous catalysts has restricted their photocatalytic capability for commercially important organic synthesis. Here, we report a way of harvesting visible light efficiently to boost zeolite catalysis by means of plasmonic gold nanoparticles (Au-NPs) supported on zeolites. Zeolites possess strong Brønsted acids and polarized electric fields created by extra-framework cations. The polarized electric fields can be further intensified by the electric near-field enhancement of Au-NPs, which results from the localized surface plasmon resonance (LSPR) upon visible light irradiation. The acetalization reaction was selected as a showcase performed on MZSM-5 and Au/MZSM-5 (M = H(+), Na(+), Ca(2+), or La(3+)). The density functional theory (DFT) calculations confirmed that the intensified polarized electric fields played a critical role in stretching the C = O bond of the reactants of benzaldehyde to enlarge their molecular polarities, thus allowing reactants to be activated more efficiently by catalytic centers so as to boost the reaction rates. This discovery should evoke intensive research interest on plasmonic metals and diverse zeolites with an aim to take advantage of sunlight for plasmonic devices, molecular electronics, energy storage, and catalysis.
| S-EPMC3898204 | biostudies-literature
Project description:Laser traps provide contactless manipulation of plasmonic nanoparticles (NPs) boosting the development of numerous applications in science and technology. The known trapping configurations allow immobilizing and moving single NPs or assembling them, but they are not suitable for massive optical transport of NPs along arbitrary trajectories. Here, we address this challenging problem and demonstrate that it can be handled by exploiting phase gradients forces to both confine and propel the NPs. The developed optical manipulation tool allows for programmable transport routing of NPs to around, surround or impact on objects in the host environment. An additional advantage is that the proposed confinement mechanism works for off-resonant but also resonant NPs paving the way for transport with simultaneous heating, which is of interest for targeted drug delivery and nanolithography. These findings are highly relevant to many technological applications including micro/nano-fabrication, micro-robotics and biomedicine.
| S-EPMC5028719 | biostudies-literature
Project description:The mid-infrared spectral region opens up new possibilities for applications such as molecular spectroscopy with high spatial and frequency resolution. For example, the mid-infrared light provided by synchrotron sources has helped for early diagnosis of several pathologies. However, alternative light sources at the table-top scale would enable better access to these state-of-the-art characterizations, eventually speeding up research in biology and medicine. Mid-infrared supercontinuum generation in highly nonlinear waveguides pumped by compact fiber lasers represents an appealing alternative to synchrotrons. Here, we introduce orientation-patterned gallium arsenide waveguides as a new versatile platform for mid-infrared supercontinuum generation. Waveguides and fiber-based pump lasers are optimized in tandem to allow for the group velocities of the signal and the idler waves to match near the degeneracy point. This configuration exacerbates supercontinuum generation from 4 to 9 µm when waveguides are pumped at 2750 nm with few-nanojoule energy pulses. The brightness of the novel mid-infrared source exceeds that of the third-generation synchrotron source by a factor of 20. We also show that the nonlinear dynamics is strongly influenced by the choice of waveguide and laser parameters, thus offering an additional degree of freedom in tailoring the spectral profile of the generated light. Such an approach then opens new paths for high-brightness mid-infrared laser sources development for high-resolution spectroscopy and imaging. Furthermore, thanks to the excellent mechanical and thermal properties of the waveguide material, further power scaling seems feasible, allowing for the generation of watt-level ultra-broad frequency combs in the mid-infrared.
| S-EPMC10582246 | biostudies-literature
Project description:Considerable effort has been devoted to manipulating the optical absorption of metal nanostructures for diverse applications. However, it still remains a challenge to develop a general and flexible method to promote broadband absorption of metal nanostructures without changing their size and shape. Here, we report a new strategy of hybridizing two conceptually different optical models to realize broadband absorption enhancement of metal nanoparticles (NPs), which is enabled by constructing a core-shell heterostructure, consisting of a spherical dielectric core covered by a metal NPs interlayer and tunable semiconductor shell. This approach integrates the interfacial photon management, photoexcitation of metal NPs and injection of hot charge carriers into the semiconductor shell, and results in distinctly enhanced hot charge carrier generation and transfer, thereby boosting the broad-spectrum light driven catalysis. The structure-plasmon-catalysis interplay of the heterostructure is comprehensively studied and optimized. This proof-of-concept proves to be generally feasible by varying the type of both metal NPs and support medium, opening a new avenue to control the optoelectronic properties of materials.
| S-EPMC6335626 | biostudies-literature
Project description:Symmetric molecular motors based on two overcrowded alkenes with a notable absence of a stereogenic center show potential to function as novel mechanical systems in the development of more advanced nanomachines offering controlled motion over surfaces. Elucidation of the key parameters and limitations of these third-generation motors is essential for the design of optimized molecular machines based on light-driven rotary motion. Herein we demonstrate the thermal and photochemical rotational behavior of a series of third-generation light-driven molecular motors. The steric hindrance of the core unit exerted upon the rotors proved pivotal in controlling the speed of rotation, where a smaller size results in lower barriers. The presence of a pseudo-asymmetric carbon center provides the motor with unidirectionality. Tuning of the steric effects of the substituents at the bridgehead allows for the precise control of the direction of disrotary motion, illustrated by the design of two motors which show opposite rotation with respect to a methyl substituent. A third-generation molecular motor with the potential to be the fastest based on overcrowded alkenes to date was used to visualize the equal rate of rotation of both its rotor units. The autonomous rotational behavior perfectly followed the predicted model, setting the stage for more advanced motors for functional dynamic systems.
| S-EPMC5520950 | biostudies-literature
Project description:The influence of plasmonic coupling effects between different components in Au NRs@Cu2-x Se nanostructures on their characteristics was studied. To this aim, anisotropic Au@Cu2-x Se hetero-nanostructures with well-controlled design and optical properties were obtained. The LSPR bands of gold and copper selenide are superpositioned in the NIR region, resulting in superior photocatalytic properties of the nanostructures.
| S-EPMC9419501 | biostudies-literature
Project description:This work reports on the observation of a delocalized surface plasmon resonance (DSPR) phenomenon in linear chains of square-shaped silver nanoparticles (NP) as a function of the chain length and the distance between the nanoparticles in the chain. Transmission spectra of the silver nanoparticle chains reveal the emergence of new, red-shifted extinction peaks that depend strongly on the spacing between the nanoparticles and the polarization of the exciting light with respect to the chain axis. As the spacing between the nanoparticles in the linear chain decreases and the number of nanoparticles in the linear chain increases, the strength of the new extinction features increase strongly. These changes can be described by a tight-binding model for the coupled chain, which indicates that the origin of the phenomenon is consistent with an increased coupling between the nanoparticles. FDTD calculations reveal that the electric field is strongly enhanced between the nanoparticles in the chain. The DSPR response is found to be much more sensitive to dielectric changes than the localized surface plasmon resonance (LSPR).
| S-EPMC3901052 | biostudies-literature