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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Self‐Limiting Polymerization‐Induced Crystallization‐Driven Self‐Assembly (SL‐PI‐CDSA) Enables Templated Synthesis of Chiral Plasmonic, Hybrid 2D Hexagonal Assemblies

Examples of self-regulating synthetic self-assembly are relatively few, with most known chemical systems relying on kinetic rather than thermodynamic control. Herein, we demonstrate the rapid generation (t ≤ 5 min) of size-tunable ultralow dispersity (Ð ≤ 1.01) 2D hexagonal nanosheets governed by self-limiting self-assembly (SLSA). Self-assembly in natural systems occurs with exquisite control of structure, function, and dimension. We demonstrate that key aspects of biological assembly can be rationally applied toward the development of bottom-up approaches for the construction of chiral nanomaterials. To this end, self-limiting polymerization-induced crystallization-driven self-assembly (SL-PI-CDSA) of modular and templating aryl isocyanide (AIC) monomers yields functional 2D assemblies permitting post-polymerization/assembly modifications. Detailed study of the internal and external structure of the hexagonal nanosheets reveals topological defects which offer mechanistic insights into both their assembly and subsequent utilization. Specifically, these features enable fabrication of chiral hybrid organic–inorganic nanomaterials incorporating chiral plasmonic metal nanoparticles (MNPs). Our results suggest that the synergistic interplay of template-driven confinement and hierarchical chirality induce symmetry breaking of in situ-generated gold MNPs. We anticipate that the platform presented will facilitate fabrication of new hybrid, chiral organic–inorganic nanostructures.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Exploring the influence of interfacial solvation on electrochemical CO 2 reduction using plasmon‐enhanced vibrational sum frequency generation spectroscopy

Although interfacial solvation plays an important role in determining carbon dioxide reduction (CO 2 R) kinetics, present understanding of the potential dependent properties of the electrochemical double layer under conditions relevant for CO 2 R remains limited. This article summarizes the development and recent applications of plasmon-enhanced vibrational sum frequency generation (VSFG) spectroscopy to study the effects of cation hydration and interfacial solvation on CO 2 R using CO as a vibrational Stark reporter. Results show that electrolyte cations retain their entire solvation shell upon adsorption to inactive sites, while active sites retain only a single water layer between the gold surface and the cation. Measurements also show that the total interfacial electric field can be separated into two contributions: one from the electrochemical double layer (Stern field) and another from the polar solvation environment (Onsager field). Surprisingly, correlating VSFG spectra with reaction kinetics reveals that it is the solvation-mediated Onsager field that governs the chemical reactivity at the electrode/electrolyte interface. Measuring the interfacial water spectra during electrocatalysis also provides evidence for the proton source during H2 evolution, which competes with CO 2 R in aqueous electrolyte. These findings highlight the importance of directly probing cation hydration and interfacial solvation, which mediates reaction kinetics at electrochemical interfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Multi-Functional Applications of H-Glass Embedded with Stable Plasmonic Gold Nanoislands

Metal nanoparticles (MNPs) are synthesized using various techniques on diverse substrates that significantly impact their properties. However, among the substrate materials investigated, the major challenge is the stability of MNPs due to their poor adhesion to the substrate. Herein, it is demonstrated how a newly developed H-glass can concurrently stabilize plasmonic gold nanoislands (GNIs) and offer multifunctional applications. The GNIs on the H-glass are synthesized using a simple yet, robust thermal dewetting process. The H-glass embedded with GNIs demonstrates versatility in its applications, such as i) acting as a room temperature chemiresistive gas sensor (70% response for NO 2 gas); ii) serving as substrates for surface-enhanced Raman spectroscopy for the identifications of Nile blue (dye) and picric acid (explosive) analytes down to nanomolar concentrations with enhancement factors of 4.8 × 10 6 and 6.1 × 10 5 , respectively; and iii) functioning as a nonlinear optical saturable absorber with a saturation intensity of 18.36 × 10 15 W m -2 at 600 nm, and the performance characteristics are on par with those of materials reported in the existing literature. In conclusion, this work establishes a facile strategy to develop advanced materials by depositing metal nanoislands on glass for various functional applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Topological plasmonic modes in graphene-coated nanowire arrays

We investigate the topological edge modes of surface plasmonic polaritons (SPPs) in a two-dimensional waveguide array composed of graphene-coated nanowires. The system experiences topological phase transition by tuning the inter-layer spacing between adjacent unit cells. The topological modes emerge at the edge of topological non-trivial nanowire arrays when the intra-layer spacing is larger than the inter-layer spacing. Thanks to the strong confinement of graphene SPPs, the modal wavelength of topological edge modes can be squeezed as small as 1/20 of incident wavelength. The study provides a promising approach to realizing robust light transport beyond diffraction limit.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Realization of all-optical plasmonic MIM split square ring resonator switch

In this work, a configuration of nano plasmonic switch is proposed and investigated. The structure is comprised of the combination of split square ring and straight waveguides. Simulations are done based on Finite-Difference-Time Domain method. The structure is based on metal-insulator-metal configuration. Split square ring and straight waveguides are consisted of air, which are situated in a silver background. The proposed switch can confine light to sub-wavelength dimensions (on the order of nano meter); therefore it can be used in highly integrated optical circuits. The split square ring structure can operate both directly or reversely based on the split position. The transmitted powers in different cases of split square switch are acceptable and higher than 0.6. Therefore, the proposed switch is an appropriate candidate for highly integrated optical communication systems.

42 ENGINEERING↗
DOE OSTI2019

Simulation and analysis of different approaches towards fiber optic plasmonic sensing for detection of human-liver tissues

Three types of plasmonic sensors are applied for the detection of five types of human-liver tissues (normal N, metastatic MET, non-cancerous metastatic NMET, hepatocellular carcinoma HCC and non-cancerous hepatocellular carcinoma NHCC). The first type of the fiber with seven layers is made by a ZBLAN core surrounded by NaF, silicon, silver, graphene, Al{sub 2}O{sub 3} and liver layers. The second type of the fiber with six layers is similar to the first one but without the graphene layer. The third type of the fiber with five layers is made by a SiO{sub 2} core surrounded by GaP, gold, Al{sub 2}O{sub 3} and liver layers. For optimized thicknesses of the interior layers at a laser wavelength (1.53 μm) one obtains large values of the figure of merit and amplitude sensitivity at an angle very close to the resonance angle. The advantage of the third (second) type of the fiber for normal liver is a large figure of merit (maximum amplitude sensitivity) in comparison with that for the second (third) type of the sensor. For all variants of the sensors, the figure of merit and maximum of the amplitude sensitivity are decreasing in the same order (N, MET, NMET, NHCC and HCC) for the liver tissues.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Optimization of the frequency response of a novel GaAs plasmonic terahertz detector

Previously there was reported a new type of high-speed plasmonic THz detector that can operate at room temperature. As an extension of that work, the sensitivity of the detector was investigated over a wide range of sub-THz frequencies. The measured frequency response is not purely monotonic but exhibits oscillatory behaviour with a number of maxima and minima. Our study reveals that such frequency dependence is caused by the interference of electromagnetic waves inside the detector substrate, as the frequencies of these extrema are found to be governed by the substrate thickness. We demonstrate that sensitivity of this type of detector can be optimized for the desired operating frequency within 0.06–0.7 THz spectrum by adjusting the substrate thickness. We also show that a monotonic frequency response with eliminated minima can be achieved by mounting the detector on a specially designed silicon lens.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Quantitative monitoring of two simultaneously binding species using Label-Enhanced surface plasmon resonance

Highlights: • SPR discriminates and monitors two molecules simultaneously binding to a surface. • Accurate concentration determination of two different molecules simultaneously. • Deconstruction of a sum sensorgram into two molecular component sensorgrams. • Simultaneous measurement of binding constants of two binding molecules in a mixture. • Applicability to allosteric effects, bi-specific binders, and conformation changes. Surface plasmon resonance (SPR) is a well-established method for biomolecular interaction studies. SPR monitors the binding of molecules to a solid surface, embodied as refractive index changes close to the surface. One limitation of conventional SPR is the universal nature of the detection that results in an inability to qualitatively discriminate between different binding species. Furthermore, it is impossible to directly discriminate two species simultaneously binding to different sites on a protein, which limits the utility of SPR, for example, in the study of allosteric binders or bi-specific molecules. It is also impossible in principle to discriminate protein conformation changes from actual binding events. Here we demonstrate how Label-Enhanced SPR can be utilized to discriminate and quantitatively monitor the simultaneous binding of two different species – one dye-labeled and one unlabeled - on a standard, single-wavelength SPR instrument. This new technique increases the versatility of SPR technology by opening up application areas where the usefulness of the approach has previously been limited.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Highly efficient degradation of phenol over a Pd-BiOBr Mott–Schottky plasmonic photocatalyst

Highlights: • Pd cubes were successfully prepared and electrostatically assembled with BiOBr. • A Mott–Schottky junction may be formed between Pd and BiOBr. • Pd nanoparticles may be activated, due to SPR effect. • Pd modified BiOBr exhibited excellent activity in photocatalytic removal of phenol. - Abstract: Surface plasmonic resonance effect has been widely applied to improve oxidation activity of a photocatalyst under visible light irradiation. Palladium particles were successfully prepared, and electrostatically assembled with BiOBr in this work. Due to the differences in work function between palladium and BiOBr, a Mott–Schottky junction may be established. This junction is in favor of the separation of photogenerated charge carriers. Also, Pd particles on the surface may absorb visible-light photons and produce extra electrons to participate in the photocatalysis. The great improvement in the photocatalytic oxidation of phenol confirms the synergetic effect (SPR and Mott–Schottky junction). This work may serve as a solid evidence to confirm that surface-loaded palladium particles are capable of improving photocatalytic activity, and that electrostatic assembly may be an effective approach to load metal particles onto a surface.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Syntheses of Colloidal F:In 2 O 3 Cubes: Fluorine-Induced Faceting and Infrared Plasmonic Response

Cube-shaped nanocrystals (NCs) of conventional metals like gold and silver generally exhibit localized surface plasmon resonance (LSPR) in the visible region with spectral modes determined by their faceted shapes. Yet, faceted NCs exhibiting LSPR response in the infrared (IR) region are relatively rare. Here, we describe the colloidal synthesis of nanoscale fluorine-doped indium oxide (F:In 2 O 3 ) cubes with LSPR response in the IR region, wherein fluorine was discovered to both direct the cubic morphology and act as an aliovalent dopant. Single-crystalline 160 nm F:In 2 O 3 cubes terminated by (100) facets and concave cubes were synthesized using a colloidal heat-up method. The presence of fluorine was found to impart higher stabilization to the (100) facets through density functional theory calculations that evaluated the energetics of F-substitution at surface oxygen sites. These calculations suggest that the cubic morphology results from surface binding of F atoms. In addition, fluorine acts as an anionic aliovalent dopant in the cubic bixbyite lattice of In 2 O 3 , introducing a high concentration of free electrons leading to LSPR. We confirmed the presence of lattice fluorine dopants in these cubes using solid-state 19 F and 115 In nuclear magnetic resonance spectroscopy. The cubes exhibit narrow, shape-dependent multimodal LSPR extinction peaks due to corner- and edge-centered modes. The spatial origin of these different contributions to the spectral response is directly visualized by electron energy loss spectroscopy in a scanning transmission electron microscope.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Synthesis of Copper–Silica Core–Shell Nanostructures with Sharp and Stable Localized Surface Plasmon Resonance

Copper nanoparticles exhibit intense and sharp localized surface plasmon resonance (LSPR) in the visible region; however, the LSPR peaks become weak and broad when exposed to air due to the oxidation of Cu. In this work, the Cu nanoparticles are successfully encapsulated in SiO 2 by employing trioctyl-n-phosphine (TOP)-capped Cu nanoparticles for the sol–gel reaction, yielding an aqueous Cu–SiO 2 core–shell suspension with stable and well-preserved LSPR properties of the Cu cores. With the TOP capping, the oxidation of the Cu cores in the microemulsion was significantly reduced, thus allowing the Cu cores to sustain the sol–gel process used for coating the SiO 2 protection layer. It was found that the self-assembled TOP-capped Cu nanoparticles were spontaneously disassembled during the sol–gel reaction, thus recovering the LSPR of individual particles. During the disassembling progress, the extinction spectrum of the nanocube agglomerates evolved from a broad extinction profile to a narrow and sharp peak. For a mixture of nanocubes and nanorods, the spectra evolved to two distinct peaks during the dissembling process. The observed spectra match well with the numerical simulations. In conclusion, these Cu–SiO 2 core–shell nanoparticles with sharp and stable LSPR may greatly expand the utilization of Cu nanoparticles in aqueous environments.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Reversible Tuning of the Surface Plasmon Resonance of Indium Tin Oxide Nanocrystals by Gas-Phase Oxidation and Reduction

Heavily doped oxide nanocrystals exhibit a tunable localized surface plasmon resonance (LSPR) in the infrared, a property that is promising for applications in photonics, spectroscopy, and photochemistry. Nanocrystal carrier density and, thus, spectral response are adjustable via chemical reaction; yet, the fundamental processes that govern this behavior are poorly understood. In this work, we study the time dependence of the LSPR supported by indium tin oxide (ITO) nanocrystals during O 2 and N 2 annealing with in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). We show that the LSPR red-shifts upon oxidation in O 2 and blue-shifts to its original position upon reduction in N 2 . A reaction–diffusion model allows us to rationalize the underlying physicochemical processes and quantitatively connect nanocrystal redox chemistry, solid-state diffusion, carrier density, and the LSPR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Role of Local Conductivities in the Plasmon Reflections at the Edges and Stacking Domain Boundaries of Trilayer Graphene

Here, we employed infrared scattering-type scanning near-field optical microscopy (IR-sSNOM) to study surface plasmon polaritons (SPPs) in trilayer graphene (TLG). Our study reveals systematic differences in near-field IR spectra and SPP wavelengths between Bernal (ABA) and rhombohedral (ABC) TLG domains on SiO 2 , which can be explained by stacking-dependent intraband conductivities. We also observed that the SPP reflection profiles at ABA-ABC boundaries could be mostly accounted for by an idealized domain boundary defined by the conductivity discontinuity. However, we identified distinct shapes in the SPP profiles at the edges of the ABA and ABC TLG, which cannot be solely attributed to idealized edges with stacking-dependent conductivities. Instead, this can be explained by the presence of various edge structures with local conductivities differing from those of bulk TLGs. Our findings unveil a new structural element that can control SPP and provide insights into the structures and electronic states of the edges of few-layer graphene.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Giant Valley Splitting and Valley Polarized Plasmonics in Group V Transition-Metal Dichalcogenide Monolayers

Two-dimensional group VI transition-metal dichalcogenides (TMDs) provide a promising platform to encode and manipulate quantum information in the valleytronics. However, the two valleys are energetically degenerate, protected by time-reversal symmetry (TRS). To lift this degeneracy, one needs to break the TRS by either applying an external magnetic field or using a magnetic rare-earth oxide substrate. Here, we predict a different strategy to achieve this goal. We propose that the ferromagnetic group V TMD monolayer, in which the TRS is intrinsically broken, can produce a larger valley and spin splitting. A polarized ZnS(0001) surface is also used as a substrate, which shifts the valleys to the low-energy regime (near the Fermi level). Moreover, by calculating its collective electronic excitation behaviors, we show that such a system hosts a giant valley polarized terahertz plasmonics. Our results demonstrate a new way to design and use valleytronic devices, which are both fundamentally and technologically significant.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Isolation of a 300 kDa, Au -1400 Gold Compound, the Standard 3.6 nm Capstone to a Series of Plasmonic Nanocrystals Protected by Aliphatic-like Thiolates

Disclosed herein is a method to obtain the ~300 kDa gold–hexanethiolate compound, extracted from the Faradaurate series of smaller (3) and larger (1) homologues, thereby permitting the first measurement of its distinctive properties by methods including mass spectrometry, optical spectroscopy, electron microscopy, X-ray scattering, and diffraction. The results suggest a monocrystalline metallic core (free of twinning planes) of ~3.1 nm minimum dimension, which supports a clear plasmonic optical response, along with a diffuse exterior shell. An idealized model to account for this (and smaller) members of the series is proposed based on the completion of a convex core of regular truncated-octahedral (TO) morphology, that is, the TO (5,5) crystallite comprising 1289 sites. The diffuse layer may comprise the 240 S sites (thiolate sulfur headgroups) and 96 Au-adatom sites, giving a total composition (1385,240) and a molar mass of ~301.0 kDa (90.7% Au). The ~300 and ~400 kDa gold compounds contain Au ~1400 and Au ~2000 atoms, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Direct Visualization of Counter-Propagating Surface Plasmons in Real Space-Time

We deploy two-dimensional nano-hole arrays as resonant surface plasmon polariton (SPP) couplers that enable counter-propagation and interference-free imaging of SPP wave-packets. We monitor the spatiotemporal evolution of the resulting SPPs using two-color photoemission electron microscopy (PEEM). The measurements track the electric field envelope of the SPP in real space and time and enable direct characterization of their spatiotemporal properties in a regime where the SPP wave-packet is the principle observable. We provide an analysis of the observables for both the co- and counter-propagating directions via SPP trajectories that are recorded in tandem. Our results highlight the advantages of isolating SPPs through counter-propagation, where field-SPP interactions are suppressed.

Crampton, Kevin T.↗
DOE OSTI2019

Modeling the Cooperative Adsorption of Solid-Binding Proteins on Silica: Molecular Insights from Surface Plasmon Resonance Measurements

Combinatorially selected solid-binding peptides (SBPs) provide a versatile route for synthesizing advanced materials and devices, especially when they are installed within structurally or functionally useful protein scaffolds. However, their promise has not been fully realized because we lack a predictive understanding of SBP-material interactions. Thermodynamic and kinetic binding parameters obtained by fitting quartz crystal microbalance and surface plasmon resonance (SPR) data with the Langmuir model whose assumptions are rarely satisfied provide limited information on underpinning molecular interactions. Using SPR, we show here that a technologically useful SBP called Car9 confers proteins to which is fused a sigmoidal adsorption behavior modulated by partner identity, quaternary structure, and ionic strength. We develop a two-step cooperative model that accurately captures the kinetics of silica binding and provides insights into how SBP–SBP interactions, fused scaffold, and solution conditions modulate adsorption. Because cooperative binding can be converted to Langmuir adhesion by mutagenesis, our approach offers a path to identify and to better understand and design practically useful SBPs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Plasmonic Nonlinear Energy Transfer Enhanced Second Harmonic Generation Nanoscopy

Nonlinear optical response is a fingerprint of various physicochemical properties of materials related to symmetry, including crystallography, interfacial configuration, and carrier dynamics. However, the intrinsically weak nonlinear optical susceptibility and the diffraction limit of far-field optics restrict probing deep-subwavelength-scale nonlinear optics with measurable signal-to-noise ratio. Here, we propose an alternative approach toward efficient second harmonic generation (SHG) nanoscopy for SHG-active sample (zinc oxide nanowire; ZnO NW) using an SHG-active plasmonic nanotip. Our full-wave simulation suggests that the experimentally observed high near-field SHG contrast is possible when the nonlinear response of ZnO NW is enhanced and/or that of the tip is suppressed. Here, this result suggests possible evidence of quantum mechanical nonlinear energy transfer between the tip and the sample, modifying the nonlinear optical susceptibility. Further, this process probes the nanoscale corrosion of ZnO NW, demonstrating potential use in studying various physicochemical phenomena in nanoscale resolution.

36 MATERIALS SCIENCE↗