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DOE OSTI2018

Gold core/ceria shell-based redox active nanozyme mimicking the biological multienzyme complex phenomenon

Catalytically active individual gold (Au) and cerium oxide (CeO2) nanoparticles are well known to exhibit specific enzyme-like activities, such as natural catalase, oxidase, superoxide dismutase, and peroxidase enzymes. These activities have been maneuvered to design several biological applications such as immunoassays, glucose detection, radiation and free radical protection and tissue engineering. A functional nanozyme depicting multienzyme like properties that functions as a synthetic super enzyme has eluded the researchers in the nanoscience community for past decade. In current report, we have designed a functional multienzyme in the form of Gold (core)-CeO2 (shell) nanoparticles (Au@CeO2 CSNPs) exhibiting excellent peroxidase, catalase and superoxide dismutase enzyme-like activities that are controlled simply by tuning the pH. The reaction kinetic parameters reveal that the peroxidase-like activity of this core shell nanozyme is comparable to natural HRP enzyme. Unlike peroxidase-like activity exhibited by other nanomaterials, Au@CeO2 CSNPs showed decrease in hydroxyl radical formation, suggesting that the bio catalytic reactions are performed by efficient electron transfers. A significant enzyme-like activity of this core shell nanoparticle was conserved at extreme pH (2 – 11) and temperatures (up to 90 °C), clearly suggesting the superiority over natural enzymes. Further, the utility of peroxidase-like activity of this core shell nanoparticles was extended for the detection of glucose, which showed a linear range of detection between (100 µM – 1 mM). It is hypothesized that the proximity of the redox potentials of Au+/Au and Ce (III)/Ce (IV) may result in a redox couple promoting the multienzyme activity of core shell nanoparticles. Au@CeO2 CSNPs may open new directions for development of single platform sensors in multiple biosensing applications.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2024

Opportunities for retrieval and tool augmented large language models in scientific facilities

Upgrades to advanced scientific user facilities such as next-generation x-ray light sources, nanoscience centers, and neutron facilities are revolutionizing our understanding of materials across the spectrum of the physical sciences, from life sciences to microelectronics. However, these facility and instrument upgrades come with a significant increase in complexity. Driven by more exacting scientific needs, instruments and experiments become more intricate each year. This increased operational complexity makes it ever more challenging for domain scientists to design experiments that effectively leverage the capabilities of and operate on these advanced instruments. Large language models (LLMs) can perform complex information retrieval, assist in knowledge-intensive tasks across applications, and provide guidance on tool usage. Using x-ray light sources, leadership computing, and nanoscience centers as representative examples, we describe preliminary experiments with a Context-Aware Language Model for Science (CALMS) to assist scientists with instrument operations and complex experimentation. With the ability to retrieve relevant information from facility documentation, CALMS can answer simple questions on scientific capabilities and other operational procedures. With the ability to interface with software tools and experimental hardware, CALMS can conversationally operate scientific instruments. By making information more accessible and acting on user needs, LLMs could expand and diversify scientific facilities’ users and accelerate scientific output.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2018

Science and technology of electrochemistry at nano-interfaces: concluding remarks

The Faraday Discussion on electrochemistry at nano-interfaces presented a platform for an incredibly diverse array of advances in electrochemical nanoscience and nanotechnology. In this summary, I have identified the factors which drive the development of the science and which ultimately support many impressive technological advances described. Prime among these are the emergence of new physical behaviors when device dimensions approach characteristic physical scaling lengths, the steadily increasing importance of surfaces as device dimensions shrink, and the capacity to fabricate and utilize structures which are commensurate in size with molecules, especially biomolecules and biomolecular complexes. In this Faraday Discussion we were treated to outstanding examples of each of these nanoscience drivers to produce new, and in many cases unexpected, electrochemical phenomena that would not be observed at larger scales. Here, the main thrust of these collective activities has been to realize the promise implicit in several transformational experiments that were carried out in the last decades of the 20th century. Our task is not complete, and we can look forward to many additional developments springing from the same intellectual wellhead.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Beyond crystallography: Diffractive imaging using coherent x-ray light sources

X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century.

Miao, Jianwei↗

DOE OSTI2011

Calix 2007:9th International Conference on Calixarene Chemistry

The DOE funds helped support an International Conference, Calix 2007, whose focus was on Supramolecular Chemistry. The conference was held at the University of Maryland from August 6-9, 2007 (Figure 1). The conference website is at www.chem.umd.edu/Conferences/Calix2007. This biannual conference had previously been held in the Czech Republic (2005), Canada (2003), Netherlands (2001), Australia (1999), Italy (1997), USA (Fort Worth, 1995) Japan (1993) and Germany (1991). Calixarenes are cup-shaped compounds that are a major part of Supramolecular Chemistry, for which Cram, Lehn and Pederson were awarded a Nobel Prize 20 years ago. Calixarene chemistry has expanded greatly in the last 2 decades, as these compounds are used in synthetic and mechanistic chemistry, separations science, materials science, nanoscience and biological chemistry. The organizing committee was quite happy that Calix 2007 encompassed the broad scope and interdisciplinary nature of the field. Our goal was to bring together leading scientists interested in calixarenes, molecular recognition, nanoscience and supramolecular chemistry. We believe that new research directions and collaborations resulted from an exchange of ideas between conferees. This grant from the DOE was crucial toward achieving that goal, as the funds helped cover some of the registration and accommodations costs for the speakers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2011

2011 Clusters, Nanocrystals & Nanostructures Gordon Research Conference

Small particles have been at the heart of nanoscience since the birth of the field and now stand ready to make significant contributions to the big challenges of energy, health and sustainability. Atomic clusters show exquisite size-dependent electronic and magnetic properties and offer a new level of control in catalyses, sensors and biochips; functionalised nanocrystals offer remarkable optical properties and diverse applications in electronic devices, solar energy, and therapy. Both areas are complemented by a raft of recent advances in fabrication, characterization, and performance of a diversity of nanomaterials from the single atom level to nanowires, nanodevices, and biologically-inspired nanosystems. The goal of the 2011 Gordon Conference is thus to continue and enhance the interdisciplinary tradition of this series and discuss the most recent advances, fundamental scientific questions, and emerging applications of clusters, nanocrystals, and nanostructures. A single conference covering all aspects of nanoscience from fundamental issues to applications has the potential to create new ideas and stimulate cross fertilization. The meeting will therefore provide a balance among the three sub-components of the conference, true to its title, with a selection of new topics added to reflect rapid advances in the field. The open atmosphere of a Gordon conference, emphasizing the presentation of unpublished results and extensive discussions, is an ideal home for this rapidly developing field and will allow all participants to enjoy a valuable and stimulating experience. Historically, this Gordon conference has been oversubscribed, so we encourage all interested researchers from academia, industry, and government institutions to apply as early as possible. We also encourage all attendees to submit their latest results for presentation at the poster sessions. We anticipate that several posters will be selected for 'hot topic' oral presentations. Given the important role students and postdocs play in the future of this field, we also anticipate several talks of this kind from young investigators.

14 SOLAR ENERGY↗

DOE OSTI2010

Terrestrial nanoparticles and their controls on soil/geo processes and reactions

This review article provides insights on some unique properties of nanoparticles (NPs) that are present in soils. In addition, this review discusses the role of NPs in controlling or influencing single and/or coupled physical, chemical, biological and hydrological soil- and/or geo-processes, which directly or indirectly affect the mobility or may determine the ultimate fate of aqueous and sorbed (adsorbed or precipitated) chemical species of nutrients and contaminants in terrestrial ecosystems. The paper is composed of 5 review sections, followed by another section on future research directions, the acknowledgements and the list of the references. A brief introduction to nanotechnology, nanoscience and environmental soil nanoscience, and definitions of relevant terms and chapter objectives are provided in the first section. A discussion on size dependent properties and controls, focusing initially on the differences in nano vs. bulk scale properties, and later on the properties that change within the nano scale, is presented in the second section. The important topic of NP origin (natural or manufactured) and occurrence in soils is presented in the third section. The behavior of NPs in soils is discussed in the fourth section. Two subsections are included. In the first one, processes that may affect NPs behavior in soils, such as growth, stability (dissolution), solid phase transformation, aggregation and aging are discussed. In the second one, processes that may be affected by the presence of NPs in soils, such as contaminant and/or nutrient sorption, redox reactions and their advective or diffusive mobility, are discussed. A brief discussion on NPs toxicity is presented in the fifth and last review section of this chapter.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2014

Magnetic nanostructuring and overcoming Brown's paradox to realize extraordinary high-temperature energy products

Nanoscience has been one of the outstanding driving forces in technology recently, arguably more so in magnetism than in any other branch of science and technology. Due to nanoscale bit size, a single computer hard disk is now able to store the text of 3,000,000 average-size books, and today’s high-performance permanent magnets—found in hybrid cars, wind turbines, and disk drives—are nanostructured to a large degree. The nanostructures ideally are designed from Co- and Fe-rich building blocks without critical rare-earth elements, and often are required to exhibit high coercivity and magnetization at elevated temperatures of typically up to 180 6C for many important permanent-magnet applications. Here we achieve this goal in exchange-coupled hard-soft composite films by effective nanostructuring of high-anisotropy HfCo7 nanoparticles with a high-magnetization Fe65Co35 phase. An analysis based on a model structure shows that the soft-phase addition improves the performance of the hard-magnetic material by mitigating Brown’s paradox in magnetism, a substantial reduction of coercivity from the anisotropy field. The nanostructures exhibit a high room-temperature energy product of about 20.3 MGOe (161.5 kJ/m3 ), which is a record for a rare earth- or Pt-free magnetic material and retain values as high as 17.1 MGOe (136.1 kJ/m3 ) at 1806C.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2020

Nanostructures for Electrical Energy Storage (NEES) (2020 Final Technical Report)

Nanostructures for Electrical Energy Storage (NEES, www.efrc.umd.edu) was an Energy Frontier Research Center supported by the DOE Office of Science, Basic Energy Sciences, from 8/1/2009 to 7/31/2020. Led by the University of Maryland, NEES enjoyed extensive collaborations with its funded partners, including two DOE Laboratories and six universities. The NEES vision has been to reveal a set of scientific insights and design principles that can underpin a next-generation electrical energy storage approach, building on advances in nanoscale science and technology to achieve simultaneous high power and high energy over extended charge/discharge cycling. The vision is motivated by the recognition that scaling into the nano regime opens the door to new physical phenomena and that the tools enlisted in nanoscale research provide major new opportunities for the synthesis not only of materials at molecular scale but for structures at nano scale and above. NEES has translated this vision into its research program based on two observations. First, while the behavior of ions and electrons in electrolytes and in electrode materials is crucial to electrical energy storage (or more appropriately electrochemical energy storage), it is the transport of ion and electron charge between different structural components of a storage device that ultimately determine its performance. With it well recognized that the choice of electrode materials typically constrain ion transport kinetics as well as maximum ion concentration, the search for better electrode materials has been a primary driver of battery research. At the same time the synthesis of electrodes is typically based on aggregation of particles with varying size, shape, and orientation in the electrode. Together with the presence of additional materials to impart electrical conductivity and cohesion to the composite electrode, change in electrode materials is necessarily accompanied by structural changes at the nano/micro scale that are difficult to categorize and manage. From the beginning, NEES’ vision has been to create and study simpler, highly controlled spatial arrangements of known materials as battery components (electrodes, current collectors, and electrolyte) and to understand how design and structure above the molecular scale determines the energy storage performance available from known materials. Second, advances in nanoscience dramatically expanded the portfolio of synthesis methods, structural motifs, and new phenomena available for research. Some of these gave rapid access to new building blocks at the deep nanoscale (e.g., carbon nanotubes grown by self-assembly, nanoscale arrays formed by electrochemical self-alignment, monolayer films controlled by self-limiting reaction). Such advances served as the enabler for the NEES vision to be pursued experimentally through study of 3D structures created and controlled at the nano, micro, and meso scales. Here, we use meso as in the BES MESO Report, implying not only intermediate or varying length scales, but very much the way behavior is influenced by other factors including aggregation of nanocomponents at different densities and spatial configurations, statistical variations in the aggregates, hierarchical architectures in which they can be assembled, or local 3D configurations that result from the architectures. Over its life cycle, NEES has pursued two overarching goals: (1) to understand the scientific fundamentals of electrochemical storage from the nanoscale to the mesoscale; and (2) to create and learn from innovative, controlled, heterogeneous nanostructures, where such nanostructures can enable the first goal and serve as models for future paradigms in energy storage. Specific goals have included: Synthesize heterogeneous nanostructures comprised of multiple materials arranged in controlled fashion and characterize their behavior; Demonstrate and elucidate design principles for achieving simultaneous high power and high energy; Develop materials processes which enable precision control of thin layers and 3D structures; Investigate the impact of artificial interphases on electrode stability during ion insertion/deinsertion; Create dense arrays of nanostructures to understand how the architecture of these assemblies, along with nanostructure design, influences energy storage behavior at the mesoscale; Identify and understand the consequences of nanoconfinement and local inhomogeneities in 3D mesoscale arrays; Develop and apply computational models to stimulate, guide and interpret experiments.

25 ENERGY STORAGE↗

DOE OSTI2012

Development and Application of Multiple-Probe Scanning Probe Microscopes

the research of advanced materials based on nanoscience and nanotechnology, it is often desirable to measure nanoscale local electrical conductivity at a designated position of a given sample. For this purpose, multiple-probe scanning probe microscopes (MP-SPMs), in which two, three or four scanning tunneling microscope (STM) or atomic force microscope (AFM) probes are operated independently, have been developed. Each probe in an MP-SPM is used not only for observing high-resolution STM or AFM images but also for forming an electrical contact enabling nanoscale local electrical conductivity measurement. The world's first double-probe STM (DP-STM) developed by the authors, which was subsequently modified to a triple-probe STM (TP-STM), has been used to measure the conductivities of one-dimensional metal nanowires and carbon nanotubes and also two-dimensional molecular films. A quadruple-probe STM (QP-STM) has also been developed and used to measure the conductivity of two-dimensional molecular films without the ambiguity of contact resistance between the probe and sample. Moreover, a quadruple-probe AFM (QP-AFM) with four conductive tuning-fork-type self-detection force sensing probes has been developed to measure the conductivity of a nanostructure on an insulating substrate. A general-purpose computer software to control four probes at the same time has also been developed and used in the operation of the QP-AFM. These developments and applications of MP-SPMs are reviewed in this paper.

36 MATERIALS SCIENCE↗

DOE OSTI2017

On the Non-Metallicity of 2.2 nm Au 246 (SR) 80 Nanoclusters

The transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. Here, we report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Electrocatalytic interface based on novel carbon nanomaterials for advanced electrochemical sensors

The rapid development of nanoscience and nanotechnology provides new opportunities for the sustainable progress of nanoscale catalysts (i.e., nanocatalysts). The introduction of nanocatalysts into electronic devices implants their novel functions into electronic sensing systems, resulting in the testing of many advanced electrochemical sensors and the fabrication of some highly sensitive, selective, and stable sensing platforms. In this Review, we will summarize recent significant progress on exploring advanced carbon nanomaterials (such as carbon nanotubes, graphene, highly ordered mesoporous carbons, and electron cyclotron resonance sputtered nanocarbon film) as nanoscale electrocatalysts (i.e., nanoelectrocatalysts) for constructing the catalytic nanointerfaces of electronic devices to achieve high-sensitivity and high-selectivity electrochemical sensors. Furthermore, different mechanisms for the extraordinary and unique electrocatalytic activities of these carbon nanomaterials will be also highlighted, compared and discussed. An outlook on the future trends and developments in this area will be provided at the end. Notably, to elaborate the nature of carbon nanomaterial, we will mainly focus on the electrocatalysis of single kind of carbon materials rather than their hybrid composite materials. As a result, we expect that advanced carbon nanomaterials with unique electrocatalytic activities will continue to attract increasing research interest and lead to new opportunities in various fields of research.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Atomic-Level Sculpting of Crystalline Oxides: Toward Bulk Nanofabrication with Single Atomic Plane Precision

We demonstrate atomic-level sculpting of 3D crystalline oxide nanostructures from metastable amorphous layer in a scanning transmission electron microscope (STEM). Strontium titanate nanostructures grow epitaxially from the crystalline substrate following the beam path. This method can be used for fabricating crystalline structures as small as 1-2 nm and the process can be observed in situ with atomic resolution. We further demonstrate fabrication of arbitrary shape structures via control of the position and scan speed of the electron beam. Combined with broad availability of the atomic resolved electron microscopy platforms, these observations suggest the feasibility of large scale implementation of bulk atomic-level fabrication as a new enabling tool of nanoscience and technology, providing a bottom-up, atomic-level complement to 3D printing.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2021

Sculpting the Plasmonic Responses of Nanoparticles by Directed Electron Beam Irradiation

Spatial confinement of matter in functional nanostructures has propelled these systems to the forefront of nanoscience, both as a playground for exotic physics and quantum phenomena and in multiple applications including plasmonics, optoelectronics, and sensing. In parallel, the emergence of monochromated electron energy loss spectroscopy (EELS) has enabled exploration of local nanoplasmonic functionalities within single nanoparticles and the collective response of nanoparticle assemblies, providing deep insight into associated mechanisms. However, modern synthesis processes for plasmonic nanostructures are often limited in the types of accessible geometry, and materials and are limited to spatial precisions on the order of tens of nm, precluding the direct exploration of critical aspects of the structure-property relationships. Here, the atomic-sized probe of the scanning transmission electron microscope is used to perform precise sculpting and design nanoparticle configurations. Using low-loss EELS, dynamic analyses of the evolution of the plasmonic response are provided. It is shown that within self-assembled systems of nanoparticles, individual nanoparticles can be selectively removed, reshaped, or patterned with nanometer-level resolution, effectively modifying the plasmonic response in both space and energy. This process significantly increases the scope for design possibilities and presents opportunities for unique structure development, which are ultimately the key for nanophotonic design.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2015

Shape transformation of bimetallic Au–Pd core–shell nanocubes to multilayered Au–Pd–Au core–shell hexagonal platelets

Transformation of metallic or bimetallic (BM) nanoparticles (NPs) from one shape to another desired shape is of importance to nanoscience and nanotechnology, where new morphologies of NPs lead to enhancement of their exploitable properties. In this report, we present the shape transformation of Au octahedral NPs to Au–Pd core–shell nanocubes, followed by their transformation to nanostars and finally to multilayered Au–Pd–Au core–shell hexagonal platelets in the presence of T30 DNA. The weaker binding affinity of T30 DNA directs the growth to favor the formation of lower energy {111} facets, changing the morphology from nanocubes to nanostar. The nanostars, exhibiting unusual intermediate morphologies, are comprised two sets of shell layers and have Au core, Pd intermediate shell, and Au outer shell. Similarly, the hexagonal platelets, which also have Au core and inner Pd shell, are encased in an external gold shell. As a result, the formation of multilayered Au–Pd–Au core–shell hexagonal platelets from Au–Pd core–shell nanocubes via the multilayered nanostars is monitored using scanning/transmission electron microscopy analysis.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2022

Importance of Standardizing Analytical Characterization Methodology for Improved Reliability of the Nanomedicine Literature

Understanding the interaction between biological structures and nanoscale technologies, dubbed the nano-bio interface, is required for successful development of safe and efficient nanomedicine products. The lack of a universal reporting system and decentralized methodologies for nanomaterial characterization have resulted in a low degree of reliability and reproducibility in the nanomedicine literature. As such, there is a strong need to establish a characterization system to support the reproducibility of nanoscience data particularly for studies seeking clinical translation. Here, we discuss the existing key standards for addressing robust characterization of nanomaterials based on their intended use in medical devices or as pharmaceuticals. We also discuss the challenges surrounding implementation of such standard protocols and their implication for translation of nanotechnology into clinical practice. We, however, emphasize that practical implementation of standard protocols in experimental laboratories requires long-term planning through integration of stakeholders including institutions and funding agencies.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2018

Ultrasound assisted sonochemically engineered effective red luminescent labeling agent for high resolution visualization of latent fingerprints

Highlights: • BaTiO{sub 3}:Eu{sup 3+} NPs were prepared by facile bio-template assisted sonochemical route. • The obtained samples displayed superstructures of various regular morphological shapes. • The optimized product was used for forensic and anti-counterfeiting applications. • CIE, CCT studies indicate the present phosphor was highly useful in LED’s. - Abstract: Nanoscience and technology finds wide range of benefits in the area of surface based science due to its nano size and high surface area. This offers new potentials in surface-based science comprising latent fingerprint (LFP) and to develop luminescent ink for anti-counterfeiting applications. Due to high backward hindrance, low sensitivity, complicated setup, and poor universality of traditionally developed techniques were main drawbacks for the visualization of LFPs. To overcome these problems, we explored the superstructures (SS) of europium ions doped BaTiO{sub 3} nanophosphors (NPs) prepared via sonochemical route with bio-template as surfactant for the detection of LFPs and as an anti-counterfeiting ink. The morphologies of SS were highly dependent on the concentration of Aloe vera (A.V.) gel as well as ultrasound irradiation time. The obtained SS displayed pure red emission which corresponds to the {sup 5}D{sub 0} → {sup 7}F{sub J} transitions of Eu{sup 3+} ions under UV light. The results clearly evident that the optimized BaTiO{sub 3}:Eu{sup 3+} NPs will create a new prospect for research in LFPs visualization and anti-counterfeiting technology.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2019

Plasmonic Surface Lattice Resonances: Theory and Computation

In overview, plasmonic surface lattice resonances (Plasmonic SLRs) are mixed light-matter states emergent in a system of periodically arranged metallic nanoparticles (NPs) under the constraint that the array spacing is approximately equal to an integer multiple of the wavelength of optical frequency light divided by the index of refraction of the surrounding medium. The properties of SLRs derive from two separate physical effects; the electromagnetic (plasmonic) response of metal NPs, and the electromagnetic states (photonic cavity modes) associated with the array of NPs. Metal NPs, especially free electron metals such as silver, gold, aluminum and alkali metals, support optical-frequency electron density oscillations known as localized surface plasmons (LSPs). The high density of conduction-band electrons for these metals gives rise to plasmon excitations that strongly couple to light even for particles that are several orders of magnitude smaller than the wavelength of the excitation source. In this sense, LSPs have the remarkable ability to squeeze far-field light into intensely-localized near-electric-fields that can enhance the intensity of light by factors of ~ 10 3 or more. Moreover, due to advances in the synthesis and fabrication of NPs, the intrinsic dependence of LSPs on NP geometry, composition, and size can readily be exploited to design NPs with a wide range of optical properties. One drawback in using LSPs to enhance optical, electronic, or chemical processes is the losses introduced into the system by via dephasing and Ohmic damping - an effect which must either be tolerated or mitigated. Plasmonic SLRs enable the mitigation of loss effects through the coupling of LSPs to diffractive states that arise from arrays satisfying Bragg scattering conditions, also known as Rayleigh anomalies (RAs). Bragg modes are well known for arrays of dielectric NPs, where they funnel and trap incoming light into the plane of the lattice, defining a photonic cavity. The low losses and narrow linewidths associated with dielectric NPs produce Bragg modes that oscillate for ~ 10 3 - 10 4 cycles before decaying. These modes are of great interest to the meta-materials community but have relatively weak electric fields associated with dielectric NPs, and therefore are not used for applications where local field enhancements are needed. Plasmonic lattices, i.e., photonic crystals composed of metallic NPs, combine the characteristics from both LSPs and diffractive states, enabling both enhanced local fields and narrow linewidth excitations, in many respects providing the best advantages of both materials. Thus, by controlling the periodicity and global symmetry of the lattice, in addition to the material composition and shape of the constituent NPs, SLRs can be designed to simultaneously survive for up to 10 3 cycles while maintaining the electric field enhancements near the NP surface that have made the use of LSPs ubiquitous in nanoscience. Modern fabrication methods allow for cm 2 -scale patches of two-dimensional (2D) arrays that are composed of approximately one trillion NPs, making them effectively infinite at the nanoscale. Because of these advances, it is now possible to experimentally realize SLRs with properties that approach those predicted by idealized theoretical models. In this Account, we introduce the fundamental theory of both SLRs and SLR-mediated lasing, where the latter is one of the most important applications of plasmonic SLRs that has emerged to date. The focus of this article is on theoretical concepts for describing plasmonic SLRs and computational methods used for their study, but throughout we emphasize physical insights provided by the theory that aid in making applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗