R-3 Repository :: Browsing by Author "Nordlander, Peter"

Browsing by Author "Nordlander, Peter"

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A Comparison of Plasmon-induced and Photoexcited Hot Carriers in Metallic Nanostructures
(2015-12-02) Zhao, Hangqi; Halas, Naomi; Nordlander, Peter; Link, Stephan
The incompressible oscillations of electrons in metallic nanostructures, known as surface plasmons, have provided a promising route to increasing light-matter coupling and boosting the efficiency of solar energy conversion in photovoltaic devices. When plasmons decay, energetic electron-hole pairs are created through a non-radiative channel. These hot electrons have found applications in photodetection and photocatalysis but remain poorly understood in terms of mechanisms. In this work1, we made a comprehensive comparison between plasmon-induced hot carrier generation and direct excitations of hot carriers by photon absorption. Using a gold nanowire based hot carrier device, which either forms a Schottky barrier or an Ohmic barrier between nanostructures and a wide-bandgap semiconductor substrate, we are able to distinguish between these two mechanisms of hot carrier generation. We show that plasmon-induced hot electrons have higher energies than directly excited carriers, and can be characterized by the integration of electrical field enhancement within the nanostructures, while photoexcited carriers are correlated with material absorption. Our work paves the way for increasing the energy conversion efficiency by decreasing the Schottky barrier and collecting both the plasmonic and interband photocurrent, which may find wide applications in future photovoltaic devices.
A First Principles Approach to Understand Plasmonic Properties in Physical Systems
(2018-11-28) Zhang, Runmin; Nordlander, Peter
Plasmonic resonances in multiple systems are theoretically investigated with a first principles approach. The plasmonic behaviors of doped semiconductor nanocrystals are explored with a quantum TDLDA approach and a classical hybridization theory. The origins and properties of plasmonic resonances from a wide variety of physical systems are explored using rigorous quantum mechanical computations. A universal metrics, the generalized plasmonicity index, is proposed to classify plasmonic resonances from other optical resonances. Using the generalized plasmonicity index, the plasmonicity of optical resonances in multiple systems are quantified, including jellium spheres, atomic-scale metallic clusters, nanostructured graphene, and polycyclic aromatic hydrocarbons. The generalized plasmonicity index provides a rigorous way to quantify the plasmonic behaviors in ultra-small systems. It also offers a quantitative foundation for the design of devices based on molecular plasmonics.
A quantitative approach to discover predictors of biodistribution for drug delivery vectors in cancer.
(2019-04-19) Nizzero, Sara; Nordlander, Peter; Ferrari, Mauro; Pimpinelli, Alberto
Systemic aspects of cancer simultaneously offer the biggest clinical challenge and the most promising therapeutic niche in the treatment of solid tumors. In fact, treatment often fails in late stages due to the presence of metastasis, a migratory phenotype of cancer invasion. Metastases consist in cancer spread to distant organs which often presents characteristic high levels of heterogeneity and acquired resistance to treatments. Multi-stage injectable delivery vectors have proven powerful in exploiting systemic transport properties connected to physiological parameters to enhance tumor accumulation and directly improve therapeutic efficacy. The theoretical framework in which these concepts first developed is now known by the term transport oncophysics: the study of mass transport phenomena relevant to oncology with a physics-based approach. For injectable inorganic delivery vectors, the major innovation relies on the capability to tailor their organ distribution (biodistribution) upon injection. This capability comes from the controllable design of such systems, which present a discoidal shape with sizes in the micrometer range. While these systems have shown disruptive results in the treatment of triple negative breast cancer metastasis, there is still a lack of fundamental understanding on how patient-specific physiological parameters affect their biodistribution. However, it is well known that patient physiology is often dysregulated in cancer patients. These alterations can be caused by a multitude of reasons: cancer itself, the presence of concurring diseases or conditions, and previous treatment. This patient heterogeneity poses an additional challenge in therapeutic translation of injectable delivery systems. In this work, significant clinically relevant physiological parameters are screened, systematically altered, and quantitatively characterized as transport barriers for systemic delivery. Systematic in vivo biodistribution studies are conducted to address changes in biodistribution resulting from controlled alteration of specific physiological parameters. Uptake kinetic is characterized through time-resolved analysis, and investigated to inform on synergistic relationships among different parameters. A computational approach is then developed to identify a pharmacokinetic (PK) model able to predict the system behavior, and used to investigate the importance of several parameters, and functional relationships. This combined in vivo / in silico approach enables the quantitative description of mechanistic rules that determine the biodistribution of systemically injected delivery vectors. The framework that emerges from this study opens the way to a new paradigm for personalized adaptive therapy, where quantitative measurements, systematic analysis, and mathematical modeling can be combined to investigate and characterize functional relationships between quantitatively characterized physiological parameters and clinically relevant measurables for injectable inorganic delivery vectors.
A room-temperature mid-infrared photodetector for on-chip molecular vibrational spectroscopy
(AIP Publishing, 2018) Zheng, Bob; Zhao, Hangqi; Cerjan, Ben; Yazdi, Sadegh; Ringe, Emilie; Nordlander, Peter; Halas, Naomi J.; Laboratory for Nanophotonics
Infrared (IR) photodetection is of major scientific and technical interest since virtually all molecules exhibit characteristic vibrational modes in the mid-infrared region of the spectrum, giving rise to molecular spectroscopy and chemical imaging in this wavelength range. High-resolution IR spectroscopies, such as Fourier Transform IR spectroscopy, typically require large, bulky optical measurement systems and expensive photodetector components. Here, we present a high-responsivity photodetector for the mid-IR spectral region which operates at room temperature. Fabricated from silicon and aluminum, the photodetection mechanism is based on free carrier absorption, giving rise to a photoresponse rivalling commercially available cooled IR photodetectors. We demonstrate that infrared spectra of molecules deposited on this detector can be obtained by a direct electrical read-out. This work could pave the way for simple, fully integrated chemical sensors and other applications, such as chemical imaging, which would benefit from the combination of mid-IR detection, room-temperature operation, and ultracompact portability.
A single molecule immunoassay by localized surface plasmon resonance
(IOP Publishing, 2010) Mayer, Kathryn M.; Hao, Feng; Lee, Seunghyun; Nordlander, Peter; Hafner, Jason H.
Absorption Spectroscopy of an Individual Fano Cluster
(American Chemical Society, 2016) Yorulmaz, Mustafa; Hoggard, Anneli; Zhao, Hangqi; Wen, Fangfang; Chang, Wei-Shun; Halas, Naomi J.; Nordlander, Peter; Link, Stephan; Laboratory for Nanophotonics
Plasmonic clusters can exhibit Fano resonances with unique and tunable asymmetric line shapes, which arise due to the coupling of bright and dark plasmon modes within each multiparticle structure. These structures are capable of generating remarkably large local electromagnetic field enhancements and should give rise to high hot carrier yields relative to other plasmonic nanostructures. While the scattering properties of individual plasmonic Fano resonances have been characterized extensively both experimentally and theoretically, their absorption properties, critical for hot carrier generation, have not yet been measured. Here, we utilize single-particle absorption spectroscopy based on photothermal imaging to distinguish between the radiative and nonradiative properties of an individual Fano cluster. In observing the absorption spectrum of individual Fano clusters, we directly verify the theoretical prediction that while Fano interference may be prominent in scattering, it is completely absent in absorption. Our results provide microscopic insight into the nature of Fano interference in systems of coupled plasmonic nanoparticles and should pave the way for the optimization of hot carrier production using plasmonic Fano clusters.
Active quantum plasmonics
(AAAS, 2015) Marinica, Dana Codruta; Zapata, Mario; Nordlander, Peter; Kazansky, Andrey K.; Echenique, Pedro M.; Aizpurua, Javier; Borisov, Andrei G.; Laboratory for Nanophotonics
The ability of localized surface plasmons to squeeze light and engineer nanoscale electromagnetic fields through electron-photon coupling at dimensions below the wavelength has turned plasmonics into a driving tool in a variety of technological applications, targeting novel and more efficient optoelectronic processes. In this context, the development of active control of plasmon excitations is a major fundamental and practical challenge. We propose a mechanism for fast and active control of the optical response of metallic nanostructures based on exploiting quantum effects in subnanometric plasmonic gaps. By applying an external dc bias across a narrow gap, a substantial change in the tunneling conductance across the junction can be induced at optical frequencies, which modifies the plasmonic resonances of the system in a reversible manner. We demonstrate the feasibility of the concept using time-dependent density functional theory calculations. Thus, along with two-dimensional structures, metal nanoparticle plasmonics can benefit from the reversibility, fast response time, and versatility of an active control strategy based on applied bias. The proposed electrical manipulation of light using quantum plasmonics establishes a new platform for many practical applications in optoelectronics.
All-Optically Reconfigurable Plasmonic Metagrating for Ultrafast Diffraction Management
(American Chemical Society, 2021) Schirato, Andrea; Mazzanti, Andrea; Proietti Zaccaria, Remo; Nordlander, Peter; Alabastri, Alessandro; Della Valle, Giuseppe; Laboratory for Nanophotonics
Hot-electron dynamics taking place in nanostructured materials upon irradiation with fs-laser pulses has been the subject of intensive research, leading to the emerging field of ultrafast nanophotonics. However, the most common description of nonlinear interaction with ultrashort laser pulses assumes a homogeneous spatial distribution for the photogenerated carriers. Here we theoretically show that the inhomogeneous evolution of the hot carriers at the nanoscale can disclose unprecedented opportunities for ultrafast diffraction management. In particular, we design a highly symmetric plasmonic metagrating capable of a transient symmetry breaking driven by hot electrons. The subsequent power imbalance between symmetrical diffraction orders is calculated to exceed 20% under moderate (∼2 mJ/cm2) laser fluence. Our theoretical investigation also indicates that the recovery time of the symmetric configuration can be controlled by tuning the geometry of the metaatom, and can be as fast as 2 ps for electrically connected configurations.
Aluminum Nanocrystals
(American Chemical Society, 2015) McClain, Michael J.; Schlather, Andrea E.; Ringe, Emilie; King, Nicholas S.; Liu, Lifei; Manjavacas, Alejandro; Knight, Mark W.; Kumar, Ish; Whitmire, Kenton; Everitt, Henry O.; Nordlander, Peter; Halas, Naomi J.; Laboratory for Nanophotonics
We demonstrate the facile synthesis of high purity aluminum nanocrystals over a range of controlled sizes from 70 to 220 nm diameter with size control achieved through a simple modification of solvent ratios in the reaction solution. The monodisperse, icosahedral, and trigonal bipyramidal nanocrystals are air-stable for weeks, due to the formation of a 2-4 nm thick passivating oxide layer on their surfaces. We show that the nanocrystals support size-dependent ultraviolet and visible plasmon modes, providing a far more sustainable alternative to gold and silver nanoparticles currently in widespread use.
Applications of Nanophotonic Photothermal Effects and Their Theoretical Modeling
(2019-11-15) Yang, Jian; Nordlander, Peter
Many of the fascinating applications of nanophotonics utilize the photothermal effects in which nanophotonic resonances enhance optical absorption and generate heat. The resulting high temperature in nanostructures has been applied in water purification, medical treatment and chemical reactions. However, theoretical modeling of nanophotonic thermal effects is often challenging because of the involved multi-physical processes. Here, we demonstrate three novel applications of nanophotonic photothermal effects with a particular emphasis on theoretical modeling: plasmon-accelerated photothermal curing of epoxy, optical-force-dominated directional reshaping of photothermally softened nanoparticles, and photothermoelectric effect in a semiconductor device. Our models successfully explained the experimental findings and gave us deeper understanding of the nanoscale photothermal systems.
Bound States in the Continuum for Metaphotonics
(2021-08-09) Gerislioglu, Burak; Nordlander, Peter
Identified almost a century ago by early quantum physicists, the study of bound states has become an active field of research that continues to surprise year after year with groundbreaking innovation opportunities and its connections to other research areas. Based on the physics of artificially engineered resonant metallic or all-dielectric building blocks (e.g., 3D and flatland metastructures), which can confine light at subwavelength scales and create high-density concentrations of electromagnetic energy, researchers are driving advances in nanophotonics and bringing us much closer to all-optical communication and data processing. In light of these, this thesis reports: (i) scalable plasmonic Fano-resonant metasurfaces for the generation of visible color and (ii) photonic quasi-infinite metastructures for refractometric sensing and sustainable chemistry. Chapter 1 discusses the limits and challenges associated with the fabrication of large-scale plasmonic metasurfaces because of fabrication imperfections, especially when using aluminum (Al). Chapter 2 demonstrates an all-dielectric metasurface design, made of periodic arrays of scatterers, towards next-generation thermo/photo-catalysis and refractometric sensing by exploiting the sharp resonances induced by bound states in the continuum (BICs), an intriguing concept in light-matter interactions.
Bridging quantum and classical plasmonics with a quantum-corrected model
(Macmillan Publishers Limited, 2012) Esteban, Ruben; Borisov, Andrei G.; Nordlander, Peter; Aizpurua, Javier; Laboratory for Nanophotonics
Electromagnetic coupling between plasmonic resonances in metallic nanoparticles allows for engineering of the optical response and generation of strong localized near-fields. Classical electrodynamics fails to describe this coupling across sub-nanometer gaps, where quantum effects become important owing to non-local screening and the spill-out of electrons. However, full quantum simulations are not presently feasible for realistically sized systems. Here we present a novel approach, the quantum-corrected model (QCM), that incorporates quantum-mechanical effects within a classical electrodynamic framework. The QCM approach models the junction between adjacent nanoparticles by means of a local dielectric response that includes electron tunnelling and tunnelling resistivity at the gap and can be integrated within a classical electrodynamical description of large and complex structures. The QCM predicts optical properties in excellent agreement with fully quantum mechanical calculations for small interacting systems, opening a new venue for addressing quantum effects in realistic plasmonic systems.
Charge Transfer Plasmons: Optical Frequency Conductances and Tunable Infrared Resonances
(American Chemical Society, 2015) Wen, Fangfang; Zhang, Yue; Gottheim, Samuel; King, Nicholas S.; Zhang, Yu; Nordlander, Peter; Halas, Naomi J.; Laboratory for Nanophotonics
A charge transfer plasmon (CTP) appears when an optical-frequency conductive pathway between two metallic nanoparticles is established, enabling the transfer of charge between nanoparticles when the plasmon is excited. Here we investigate the properties of the CTP in a nanowire-bridged dimer geometry. Varying the junction geometry controls its conductance, which modifies the resonance energies and scattering intensities of the CTP while also altering the other plasmon modes of the nanostructure. Reducing the junction conductance shifts this resonance to substantially lower energies in the near- and mid-infrared regions of the spectrum. The CTP offers both a high-information probe of optical frequency conductances in nanoscale junctions and a new, unique approach to controllably engineering tunable plasmon modes at infrared wavelengths.
Chiral and Achiral Nanodumbbell Dimers: The Effect of Geometry on Plasmonic Properties
(American Chemical Society, 2016) Smith, Kyle W.; Zhao, Hangqi; Zhang, Hui; Sánchez -Iglesias, Ana; Grzelczak, Marek; Wang, Yumin; Chang, Wei-Shun; Nordlander, Peter; Liz-Marzán, Luis; Link, Stephan; Laboratory for Nanophotonics
Metal nanoparticles with a dumbbell-like geometry have plasmonic properties similar to those of their nanorod counterparts, but the unique steric constraints induced by their enlarged tips result in distinct geometries when self-assembled. Here, we investigate gold dumbbells that are assembled into dimers within polymeric micelles. A single-particle approach with correlated scanning electron microscopy and dark-field scattering spectroscopy reveals the effects of dimer geometry variation on the scattering properties. The dimers are prepared using exclusively achiral reagents, and the resulting dimer solution produces no detectable ensemble circular dichroism response. However, single-particle circular differential scattering measurements uncover that this dimer sample is a racemic mixture of individual nanostructures with significant positive and negative chiroptical signals. These measurements are complemented with detailed simulations that confirm the influence of various symmetry elements on the overall peak resonance energy, spectral line shape, and circular differential scattering response. This work expands the current understanding of the influence self-assembled geometries have on plasmonic properties, particularly with regard to chiral and/or racemic samples which may have significant optical activity that may be overlooked when using exclusively ensemble characterization techniques.
Chiral Plasmonic Pinwheels Exhibit Orientation-Independent Linear Differential Scattering under Asymmetric Illumination
(American Chemical Society, 2023) McCarthy, Lauren A.; Verma, Ojasvi; Naidu, Gopal Narmada; Bursi, Luca; Alabastri, Alessandro; Nordlander, Peter; Link, Stephan
Plasmonic nanoantennas have considerably stronger polarization-dependent optical properties than their molecular counterparts, inspiring photonic platforms for enhancing molecular dichroism and providing fundamental insight into light-matter interactions. One such insight is that even achiral nanoparticles can yield strong optical activity when they are asymmetrically illuminated from a single oblique angle instead of evenly illuminated. This effect, called extrinsic chirality, results from the overall chirality of the experimental geometry and strongly depends on the orientation of the incident light. Although extrinsic chirality has been well-characterized, an analogous effect involving linear polarization sensitivity has not yet been discussed. In this study, we investigate the differential scattering of rotationally symmetric chiral plasmonic pinwheels when asymmetrically irradiated with linearly polarized light. Despite their high rotational symmetry, we observe substantial linear differential scattering that is maintained over all pinwheel orientations. We demonstrate that this orientation-independent linear differential scattering arises from the broken mirror and rotational symmetries of our overall experimental geometry. Our results underscore the necessity of considering both the rotational symmetry of the nanoantenna and the experimental setup, including illumination direction and angle, when performing plasmon-enhanced chiroptical characterizations. Our results demonstrate spectroscopic signatures of an effect analogous to extrinsic chirality for linear polarizations.
Coherent Fano resonances in a plasmonic nanocluster enhance optical four-wave mixing
(National Academy of Sciences, 2013) Zhang, Yu; Wen, Fangfang; Zhen, Yu-Rong; Nordlander, Peter; Halas, Naomi J.; Laboratory for Nanophotonics
Plasmonic nanoclusters, an ordered assembly of coupled metallic nanoparticles, support unique spectral features known as Fano resonances due to the coupling between their subradiant and superradiant plasmon modes. Within the Fano resonance, absorption is significantly enhanced, giving rise to highly localized, intense near fields with the potential to enhance nonlinear optical processes. Here, we report a structure supporting the coherent oscillation of two distinct Fano resonances within an individual plasmonic nanocluster. We show how this coherence enhances the optical four-wave mixing process in comparison with other doubleresonant plasmonic clusters that lack this property. A model that explains the observed four-wave mixing features is proposed, which is generally applicable to any third-order process in plasmonic nanostructures. With a larger effective susceptibility χ (3) relative to existing nonlinear optical materials, this coherent double-resonant nanocluster offers a strategy for designing high-performance thirdorder nonlinear optical media.
Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles
(National Academy of Sciences, 2013) Neumann, Oara; Feronti, Curtis; Neumann, Albert D.; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J.; Laboratory for Nanophotonics; Rice Quantum Institute
The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator.
Computational chromatography: A machine learning strategy for demixing individual chemical components in complex mixtures
(PNAS, 2022) Bajomo, Mary M.; Ju, Yilong; Zhou, Jingyi; Elefterescu, Simina; Farr, Corbin; Zhao, Yiping; Neumann, Oara; Nordlander, Peter; Patel, Ankit; Halas, Naomi J.; Laboratory for Nanophotonics
Surface-enhanced Raman spectroscopy (SERS) holds exceptional promise as a streamlined chemical detection strategy for biological and environmental contaminants compared with current laboratory methods. Priority pollutants such as polycyclic aromatic hydrocarbons (PAHs), detectable in water and soil worldwide and known to induce multiple adverse health effects upon human exposure, are typically found in multicomponent mixtures. By combining the molecular fingerprinting capabilities of SERS with the signal separation and detection capabilities of machine learning (ML), we examine whether individual PAHs can be identified through an analysis of the SERS spectra of multicomponent PAH mixtures. We have developed an unsupervised ML method we call Characteristic Peak Extraction, a dimensionality reduction algorithm that extracts characteristic SERS peaks based on counts of detected peaks of the mixture. By analyzing the SERS spectra of two-component and four-component PAH mixtures where the concentration ratios of the various components vary, this algorithm is able to extract the spectra of each unknown component in the mixture of unknowns, which is then subsequently identified against a SERS spectral library of PAHs. Combining the molecular fingerprinting capabilities of SERS with the signal separation and detection capabilities of ML, this effort is a step toward the computational demixing of unknown chemical components occurring in complex multicomponent mixtures.
Cooling systems and hybrid A/C systems using an electromagnetic radiation-absorbing complex
(2015-05-19) Halas, Nancy J.; Nordlander, Peter; Neumann, Oara; Rice University; United States Patent and Trademark Office
A method for powering a cooling unit. The method including applying electromagnetic (EM) radiation to a complex, where the complex absorbs the EM radiation to generate heat, transforming, using the heat generated by the complex, a fluid to vapor, and sending the vapor from the vessel to a turbine coupled to a generator by a shaft, where the vapor causes the turbine to rotate, which turns the shaft and causes the generator to generate the electric power, wherein the electric powers supplements the power needed to power the cooling unit.
Design of All-dielectric Metasurfaces for Vacuum Ultraviolet Applications
(2020-12-04) Zhang, Ming; Nordlander, Peter
The last decade witnessed a surge in applications of all-dielectric metasurfaces. Compared to traditional plasmonic materials, low-loss, high-refractive-index dielectric materials can generate strong local electric field enhancement while maintaining low optical absorption, thus providing new possibilities in various applications, such as imaging, nonlinear generation, and biosensing. In this thesis, we explore the potential of all-dielectric metasurfaces in two aspects. In the first part of this thesis, we demonstrate two novel nonlinear all-dielectric metasurface designs in the vacuum ultraviolet (VUV) region: a titanium dioxide (TiO2) metasurface that provides enhanced third harmonic generation at 185 nm by an anapole resonance near the fundamental wavelength of 555 nm, and an ultracompact zinc oxide (ZnO) metalens that effectively converts a 394-nm wave into converging 197-nm light via second harmonic generation. In the second part of the thesis, we introduce a new automated nanodevice design (inverse design) platform based on the discrete dipole approximation method (DDA) and optimization theories. With given performance metrics, this computational platform is capable of efficiently searching for optimal nanodevice geometries without intensive human labor, thus illustrating a promising strategy for designing large-scale, multifunctional all-dielectric metasurfaces.

Browsing by Author "Nordlander, Peter"

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