Jennifer Dionne

All Publications

• Optical Helicity and Optical Chirality in Free Space and in the Presence of Matter Symmetry 2019, 11(9) Poulikakos, L. V., Dionne, J. A., Garcia-Etxarri, A. 2019; 11 (9)

  View details for DOI 10.3390/sym11091113

• Subwavelength-scale plasmon waveguides Surface Plasmon Photonics Atwater, H., Dionne, J., Sweatlock, L. edited by Brongersma, M., L., Kik, P., G. Dordrecht, NL: Springer. : 87–104
• Temperature-dependent optical properties of titanium nitride APPLIED PHYSICS LETTERS Briggs, J. A., Naik, G. V., Zhao, Y., Petach, T. A., Sahasrabuddhe, K., Goldhaber-Gordon, D., Melosh, N. A., Dionne, J. A. 2017; 110 (10)

  View details for DOI 10.1063/1.4977840

  View details for Web of Science ID 000397871800011

• Enhancing Enantioselective Absorption Using Dielectric Nanospheres ACS PHOTONICS Ho, C., Garcia-Etxarri, A., Zhao, Y., Dionne, J. 2017; 4 (2): 197-203

  View details for DOI 10.1021/acsphotonics.6b00701

  View details for Web of Science ID 000394483500001

• Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles NATURE COMMUNICATIONS Narayan, T. C., Hayee, F., Baldi, A., Koh, A. L., Sinclair, R., Dionne, J. A. 2017; 8

  View details for DOI 10.1038/ncomms14020

  View details for Web of Science ID 000391869800001

• Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles. Nature communications Narayan, T. C., Hayee, F., Baldi, A., Leen Koh, A., Sinclair, R., Dionne, J. A. 2017; 8: 14020-?

  Abstract

  Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation-the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm-to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.

  View details for DOI 10.1038/ncomms14020

  View details for PubMedID 28091597

  View details for PubMedCentralID PMC5241819

• Nanoscopic control and quantification of enantioselective optical forces Nature Nanotechnology Zhao, Y., Saleh, A., van de Haar, M., Baum, B., Briggs, J. A., Lay, A., Reyes-Becerra, O. A., Dionne, J. A. 2017: 1055–59

  Abstract

  Circularly polarized light (CPL) exerts a force of different magnitude on left- and right-handed enantiomers, an effect that could be exploited for chiral resolution of chemical compounds as well as controlled assembly of chiral nanostructures. However, enantioselective optical forces are challenging to control and quantify because their magnitude is extremely small (sub-piconewton) and varies in space with sub-micrometre resolution. Here, we report a technique to both strengthen and visualize these forces, using a chiral atomic force microscope probe coupled to a plasmonic optical tweezer. Illumination of the plasmonic tweezer with CPL exerts a force on the microscope tip that depends on the handedness of the light and the tip. In particular, for a left-handed chiral tip, transverse forces are attractive with left-CPL and repulsive with right-CPL. Additionally, total force differences between opposite-handed specimens exceed 10 pN. The microscope tip can map chiral forces with 2 nm lateral resolution, revealing a distinct spatial distribution of forces for each handedness.

  View details for DOI 10.1038/nnano.2017.180

  View details for PubMedCentralID PMC5679370

• Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers. Optics express Saleh, A. A., Sheikhoelislami, S., Gastelum, S., Dionne, J. A. 2016; 24 (18): 20593-20603

  Abstract

  Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

  View details for DOI 10.1364/OE.24.020593

  View details for PubMedID 27607663

• Enhancing Quantum Yield via Local Symmetry Distortion in Lanthanide-Based Upconverting Nanoparticles ACS PHOTONICS Wisser, M. D., Fischer, S., Maurer, P. C., Bronstein, N. D., Chu, S., Alivisatos, A. P., Salleo, A., Dionne, J. A. 2016; 3 (8): 1523-1530

  View details for DOI 10.1021/acsphotonics.6b00166

  View details for Web of Science ID 000381717600023

• Reconstructing solute-induced phase transformations within individual nanocrystals NATURE MATERIALS Narayan, T. C., Baldi, A., Koh, A. L., Sinclair, R., Dionne, J. A. 2016; 15 (7): 768-?

  Abstract

  Strain and defects can significantly impact the performance of functional nanomaterials. This effect is well exemplified by energy storage systems, in which structural changes such as volume expansion and defect generation govern the phase transformations associated with charging and discharging. The rational design of next-generation storage materials therefore depends crucially on understanding the correlation between the structure of individual nanoparticles and their solute uptake and release. Here, we experimentally reconstruct the spatial distribution of hydride phases within individual palladium nanocrystals during hydrogen absorption, using a combination of electron spectroscopy, dark-field imaging, and electron diffraction in an environmental transmission electron microscope. We show that single-crystalline cubes and pyramids exhibit a uniform hydrogen distribution at equilibrium, whereas multiply twinned icosahedra exclude hydrogen from regions of high compressive strains. Our technique offers unprecedented insight into nanoscale phase transformations in reactive environments and can be extended to a variety of functional nanomaterials.

  View details for DOI 10.1038/NMAT4620

  View details for Web of Science ID 000378347800027

  View details for PubMedID 27088234

• Roadmap on optical energy conversion JOURNAL OF OPTICS Boriskina, S. V., Green, M. A., Catchpole, K., Yablonovitch, E., Beard, M. C., Okada, Y., Lany, S., Gershon, T., Zakutayev, A., Tahersima, M. H., Sorger, V. J., Naughton, M. J., Kempa, K., Dagenais, M., Yao, Y., Xu, L., Sheng, X., Bronstein, N. D., Rogers, J. A., Alivisatos, A. P., Nuzzo, R. G., Gordon, J. M., Wu, D. M., Wisser, M. D., Salleo, A., Dionne, J., Bermel, P., Greffet, J., Celanovic, I., Soljacic, M., Manor, A., Rotschild, C., Raman, A., Zhu, L., Fan, S., Chen, G. 2016; 18 (7)

  View details for DOI 10.1088/2040-8978/18/7/073004

  View details for Web of Science ID 000383908800007

• Towards nanoscale multiplexing with parity-time-symmetric plasmonic coaxial waveguides PHYSICAL REVIEW B Alaeian, H., Baum, B., Jankovic, V., Lawrence, M., Dionne, J. A. 2016; 93 (20)

  View details for DOI 10.1103/PhysRevB.93.205439

  View details for Web of Science ID 000376639000005

• Enantioselective Optical Trapping of Chiral Nanoparticles with Plasmonic Tweezers ACS PHOTONICS Zhao, Y., Saleh, A. A., Dionne, J. A. 2016; 3 (3): 304-309

  View details for DOI 10.1021/acsphotonics.5b00574

  View details for Web of Science ID 000372479500001

• Fully CMOS-compatible titanium nitride nanoantennas APPLIED PHYSICS LETTERS Briggs, J. A., Naik, G. V., Petach, T. A., Baum, B. K., Goldhaber-Gordon, D., Dionne, J. A. 2016; 108 (5)

  View details for DOI 10.1063/1.4941413

  View details for Web of Science ID 000373055700010

• Evolution of Plasmonic Metamolecule Modes in the Quantum Tunneling Regime. ACS nano Scholl, J. A., Garcia-Etxarri, A., Aguirregabiria, G., Esteban, R., Narayan, T. C., Koh, A. L., Aizpurua, J., Dionne, J. A. 2016; 10 (1): 1346-1354

  Abstract

  Plasmonic multinanoparticle systems exhibit collective electric and magnetic resonances that are fundamental for the development of state-of-the-art optical nanoantennas, metamaterials, and surface-enhanced spectroscopy substrates. While electric dipolar modes have been investigated in both the classical and quantum realm, little attention has been given to magnetic and other "dark" modes at the smallest dimensions. Here, we study the collective electric, magnetic, and dark modes of colloidally synthesized silver nanosphere trimers with varying interparticle separation using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). This technique enables direct visualization and spatially selective excitation of individual trimers, as well as manipulation of the interparticle distance into the subnanometer regime with the electron beam. Our experiments reveal that bonding electric and magnetic modes are significantly impacted by quantum effects, exhibiting a relative blueshift and reduced EELS amplitude compared to classical predictions. In contrast, the trimer's electric dark mode is not affected by quantum tunneling for even Ångström-scale interparticle separations. We employ a quantum-corrected model to simulate the effect of electron tunneling in the trimer which shows excellent agreement with experimental results. This understanding of classical and quantum-influenced hybridized modes may impact the development of future quantum plasmonic materials and devices, including Fano-like molecular sensors and quantum metamaterials.

  View details for DOI 10.1021/acsnano.5b06738

  View details for PubMedID 26639023

• Plasmonics feature issue: publisher's note OPTICAL MATERIALS EXPRESS Boltasseva, A., Dionne, J. 2015; 5 (12): 2978-2978

  View details for DOI 10.1364/OME.5.002978

  View details for Web of Science ID 000366045900027

• Localized fields, global impact: Industrial applications of resonant plasmonic materials MRS BULLETIN Dionne, J. A., Baldi, A., Baum, B., Ho, C., Jankovic, V., Naik, G. V., Narayan, T., Scholl, J. A., Zhao, Y. 2015; 40 (12): 1138-1145

  View details for DOI 10.1557/mrs.2015.233

  View details for Web of Science ID 000365744400014

• Feature issue introduction: plasmonics OPTICAL MATERIALS EXPRESS Boltasseva, A., Dionne, J. 2015; 5 (11): 2698-2701

  View details for DOI 10.1364/OME.5.002698

  View details for Web of Science ID 000364467700034

• Photon upconversion with hot carriers in plasmonic systems APPLIED PHYSICS LETTERS Naik, G. V., Dionne, J. A. 2015; 107 (13)

  View details for DOI 10.1063/1.4932127

  View details for Web of Science ID 000362575600051

• Polymer lattices as mechanically tunable 3-dimensional photonic crystals operating in the infrared APPLIED PHYSICS LETTERS Chernow, V. F., Alaeian, H., Dionne, J. A., Greer, J. R. 2015; 107 (10)

  View details for DOI 10.1063/1.4930819

  View details for Web of Science ID 000361640200018

• Controlling electric, magnetic, and chiral dipolar emission with PT-symmetric potentials PHYSICAL REVIEW B Alaeian, H., Dionne, J. A. 2015; 91 (24)

  View details for DOI 10.1103/PhysRevB.91.245108

  View details for Web of Science ID 000355647400003

• Nanoscale optical tomography with cathodoluminescence spectroscopy NATURE NANOTECHNOLOGY Atre, A. C., Brenny, B. J., Coenen, T., Garcia-Etxarri, A., Polman, A., Dionne, J. A. 2015; 10 (5): 429-436

  Abstract

  Tomography has enabled the characterization of the Earth's interior, visualization of the inner workings of the human brain, and three-dimensional reconstruction of matter at the atomic scale. However, tomographic techniques that rely on optical excitation or detection are generally limited in their resolution by diffraction. Here, we introduce a tomographic technique--cathodoluminescence spectroscopic tomography--to probe optical properties in three dimensions with nanometre-scale spatial and spectral resolution. We first obtain two-dimensional cathodoluminescence maps of a three-dimensional nanostructure at various orientations. We then use the method of filtered back-projection to reconstruct the cathodoluminescence intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can be further correlated with the radiative local density of optical states in particular regions of the reconstruction. We demonstrate how cathodoluminescence tomography can be used to achieve nanoscale three-dimensional visualization of light-matter interactions by reconstructing a three-dimensional metal-dielectric nanoresonator.

  View details for DOI 10.1038/NNANO.2015.39

  View details for Web of Science ID 000354094900012

  View details for PubMedID 25849788

• Strain-induced modification of optical selection rules in lanthanide-based upconverting nanoparticles. Nano letters Wisser, M. D., Chea, M., Lin, Y., Wu, D. M., Mao, W. L., Salleo, A., Dionne, J. A. 2015; 15 (3): 1891-1897

  Abstract

  NaYF4:Yb(3+),Er(3+) nanoparticle upconverters are hindered by low quantum efficiencies arising in large part from the parity-forbidden nature of their optical transitions and the nonoptimal spatial separations between lanthanide ions. Here, we use pressure-induced lattice distortion to systematically modify both parameters. Although hexagonal-phase nanoparticles exhibit a monotonic decrease in upconversion emission, cubic-phase particles experience a nearly 2-fold increase in efficiency. In-situ X-ray diffraction indicates that these emission changes require only a 1% reduction in lattice constant. Our work highlights the intricate relationship between upconversion efficiency and lattice geometry and provides a promising approach to modifying the quantum efficiency of any lanthanide upconverter.

  View details for DOI 10.1021/nl504738k

  View details for PubMedID 25647523

• Lights, nano, action! New plasmonic materials and methods to probe nanoscale phenomena MRS BULLETIN Dionne, J. A. 2015; 40 (3): 264-270

  View details for DOI 10.1557/mrs.2015.31

  View details for Web of Science ID 000351157100021

• A parity-time symmetric coherent plasmonic absorber-amplifier JOURNAL OF APPLIED PHYSICS Baum, B., Alaeian, H., Dionne, J. 2015; 117 (6)

  View details for DOI 10.1063/1.4907871

  View details for Web of Science ID 000349846300006

• Probing Complex Reflection Coefficients in One-Dimensional Surface Plasmon Polariton Waveguides and Cavities Using STEM EELS. Nano letters Schoen, D. T., Atre, A. C., García-Etxarri, A., Dionne, J. A., Brongersma, M. L. 2015; 15 (1): 120-126

  Abstract

  The resonant properties of a plasmonic cavity are determined by the size of the cavity, the surface plasmon polariton (SPP) dispersion relationship, and the complex reflection coefficients of the cavity boundaries. In small wavelength-scale cavities, the phase propagation due to reflections from the cavity walls is of a similar magnitude to propagation due to traversing the cavity. Until now, this reflection phase has been inferred from measurements of the resonant frequencies of a cavity of known dispersion and length. In this work, we present a method for measuring the complex reflection coefficients of a truncation in a 1D surface plasmon waveguide using electron energy loss spectroscopy in the scanning transmission electron microscope (STEM EELS) and show that this insight can be used to engineer custom cavities with engineered reflecting boundaries, whose resonant wavelengths and internal mode density profiles can be analytically predicted given knowledge of the cavity dimensions and complex reflection coefficients of the boundaries.

  View details for DOI 10.1021/nl503179j

  View details for PubMedID 25545292

• Upconversion for Enhanced Photovoltaics 3rd Physics of Sustainable Energy (PSE) Conference Briggs, J. A., Wu, D. M., Atre, A. C., Garcia-Etxarri, A., Dionne, J. A. AMER INST PHYSICS. 2015: 33–43

  View details for DOI 10.1063/1.4916166

  View details for Web of Science ID 000354881700003

• Strain-induced modification of optical selection rules in lanthanide-based upconverting nanoparticles Nano Letters Wisser, M., Chea, M., Lin, Y., Wu, D., Mao, W. L., Salleo, A., Dionne, J. 2015: 1891–97

  Abstract

  NaYF4:Yb(3+),Er(3+) nanoparticle upconverters are hindered by low quantum efficiencies arising in large part from the parity-forbidden nature of their optical transitions and the nonoptimal spatial separations between lanthanide ions. Here, we use pressure-induced lattice distortion to systematically modify both parameters. Although hexagonal-phase nanoparticles exhibit a monotonic decrease in upconversion emission, cubic-phase particles experience a nearly 2-fold increase in efficiency. In-situ X-ray diffraction indicates that these emission changes require only a 1% reduction in lattice constant. Our work highlights the intricate relationship between upconversion efficiency and lattice geometry and provides a promising approach to modifying the quantum efficiency of any lanthanide upconverter.

  View details for DOI 10.1021/nl504738k

• In situ detection of hydrogen-induced phase transitions in individual palladium nanocrystals NATURE MATERIALS Baldi, A., Narayan, T. C., Koh, A. L., Dionne, J. A. 2014; 13 (12): 1143-1148

  View details for DOI 10.1038/NMAT4086

  View details for Web of Science ID 000345432200018

• Plasmon-Enhanced Upconversion JOURNAL OF PHYSICAL CHEMISTRY LETTERS Wu, D. M., Garcia-Etxarri, A., Salleo, A., Dionne, J. A. 2014; 5 (22): 4020-4031

  Abstract

  Upconversion, the conversion of photons from lower to higher energies, is a process that promises applications ranging from high-efficiency photovoltaic and photocatalytic cells to background-free bioimaging and therapeutic probes. Existing upconverting materials, however, remain too inefficient for viable implementation. In this Perspective, we describe the significant improvements in upconversion efficiency that can be achieved using plasmon resonances. As collective oscillations of free electrons, plasmon resonances can be used to enhance both the incident electromagnetic field intensity and the radiative emission rates. To date, this approach has shown upconversion enhancements up to 450×. We discuss both theoretical underpinnings and experimental demonstrations of plasmon-enhanced upconversion, examining the roles of upconverter quantum yield, plasmonic geometry, and plasmon spectral overlap. We also discuss nonoptical consequences of including metal nanostructures near upconverting emitters. The rapidly expanding field of plasmon-enhanced upconversion provides novel fundamental insight into nanoscale light-matter interactions while improving prospects for technological relevance.

  View details for DOI 10.1021/jz5019042

  View details for Web of Science ID 000345542900014

• Plasmon-Enhanced Upconversion. journal of physical chemistry letters Wu, D. M., García-Etxarri, A., Salleo, A., Dionne, J. A. 2014; 5 (22): 4020-4031

  Abstract

  Upconversion, the conversion of photons from lower to higher energies, is a process that promises applications ranging from high-efficiency photovoltaic and photocatalytic cells to background-free bioimaging and therapeutic probes. Existing upconverting materials, however, remain too inefficient for viable implementation. In this Perspective, we describe the significant improvements in upconversion efficiency that can be achieved using plasmon resonances. As collective oscillations of free electrons, plasmon resonances can be used to enhance both the incident electromagnetic field intensity and the radiative emission rates. To date, this approach has shown upconversion enhancements up to 450×. We discuss both theoretical underpinnings and experimental demonstrations of plasmon-enhanced upconversion, examining the roles of upconverter quantum yield, plasmonic geometry, and plasmon spectral overlap. We also discuss nonoptical consequences of including metal nanostructures near upconverting emitters. The rapidly expanding field of plasmon-enhanced upconversion provides novel fundamental insight into nanoscale light-matter interactions while improving prospects for technological relevance.

  View details for DOI 10.1021/jz5019042

  View details for PubMedID 26276488

• Parity-time-symmetric plasmonic metamaterials PHYSICAL REVIEW A Alaeian, H., Dionne, J. A. 2014; 89 (3)

  View details for DOI 10.1103/PhysRevA.89.033829

  View details for Web of Science ID 000333184400011

• Non-Hermitian nanophotonic and plasmonic waveguides PHYSICAL REVIEW B Alaeian, H., Dionne, J. A. 2014; 89 (7)

  View details for DOI 10.1103/PhysRevB.89.075136

  View details for Web of Science ID 000332419900002

• A metafluid exhibiting strong optical magnetism. Nano letters Sheikholeslami, S. N., Alaeian, H., Koh, A. L., Dionne, J. A. 2013; 13 (9): 4137-4141

  Abstract

  Advances in the field of metamaterials have enabled unprecedented control of light-matter interactions. Metamaterial constituents support high-frequency electric and magnetic dipoles, which can be used as building blocks for new materials capable of negative refraction, electromagnetic cloaking, strong visible-frequency circular dichroism, and enhancing magnetic or chiral transitions in ions and molecules. While all metamaterials to date have existed in the solid-state, considerable interest has emerged in designing a colloidal metamaterial or "metafluid". Such metafluids would combine the advantages of solution-based processing with facile integration into conventional optical components. Here we demonstrate the colloidal synthesis of an isotropic metafluid that exhibits a strong magnetic response at visible frequencies. Protein-antibody interactions are used to direct the solution-phase self-assembly of discrete metamolecules comprised of silver nanoparticles tightly packed around a single dielectric core. The electric and magnetic response of individual metamolecules and the bulk metamaterial solution are directly probed with optical scattering and spectroscopy. Effective medium calculations indicate that the bulk metamaterial exhibits a negative effective permeability and a negative refractive index at modest fill factors. This metafluid can be synthesized in large-quantity and high-quality and may accelerate development of advanced nanophotonic and metamaterial devices.

  View details for DOI 10.1021/nl401642z

  View details for PubMedID 23919764

• Surface-enhanced circular dichroism spectroscopy mediated by nonchiral nanoantennas PHYSICAL REVIEW B Garcia-Etxarri, A., Dionne, J. A. 2013; 87 (23)

  View details for DOI 10.1103/PhysRevB.87.235409

  View details for Web of Science ID 000320164900008

• NANOPLASMONICS Plasmons rock in metal bands NATURE MATERIALS Dionne, J. A. 2013; 12 (5): 380-381

  View details for DOI 10.1038/nmat3607

  View details for Web of Science ID 000317954800003

  View details for PubMedID 23503013

• A Broadband Negative Index Metamaterial at Optical Frequencies ADVANCED OPTICAL MATERIALS Atre, A. C., Garcia-Etxarri, A., Alaeian, H., Dionne, J. A. 2013; 1 (4): 327-333

  View details for DOI 10.1002/adom.201200022

  View details for Web of Science ID 000320998600009

• Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits JOURNAL OF APPLIED PHYSICS Briggs, J. A., Atre, A. C., Dionne, J. A. 2013; 113 (12)

  View details for DOI 10.1063/1.4796092

  View details for Web of Science ID 000316967800061

• Observation of Quantum Tunneling between Two Plasmonic Nanoparticles NANO LETTERS Scholl, J. A., Garcia-Etxarri, A., Koh, A. L., Dionne, J. A. 2013; 13 (2): 564-569

  Abstract

  The plasmon resonances of two closely spaced metallic particles have enabled applications including single-molecule sensing and spectroscopy, novel nanoantennas, molecular rulers, and nonlinear optical devices. In a classical electrodynamic context, the strength of such dimer plasmon resonances increases monotonically as the particle gap size decreases. In contrast, a quantum mechanical framework predicts that electron tunneling will strongly diminish the dimer plasmon strength for subnanometer-scale separations. Here, we directly observe the plasmon resonances of coupled metallic nanoparticles as their gap size is reduced to atomic dimensions. Using the electron beam of a scanning transmission electron microscope (STEM), we manipulate pairs of ~10-nm-diameter spherical silver nanoparticles on a substrate, controlling their convergence and eventual coalescence into a single nanosphere. We simultaneously employ electron energy-loss spectroscopy (EELS) to observe the dynamic plasmonic properties of these dimers before and after particle contact. As separations are reduced from 7 nm, the dominant dipolar peak exhibits a redshift consistent with classical calculations. However, gaps smaller than ~0.5 nm cause this mode to exhibit a reduced intensity consistent with quantum theories that incorporate electron tunneling. As the particles overlap, the bonding dipolar mode disappears and is replaced by a dipolar charge transfer mode. Our dynamic imaging, manipulation, and spectroscopy of nanostructures enables the first full spectral mapping of dimer plasmon evolution and may provide new avenues for in situ nanoassembly and analysis in the quantum regime.

  View details for DOI 10.1021/nl304078v

  View details for Web of Science ID 000315079500040

  View details for PubMedID 23245286

• Plasmons rock in metal bands Nature Materials 12 Dionne, J. 2013: 380
• Toward Efficient Optical Trapping of Sub-10-nm Particles with Coaxial Plasmonic Apertures NANO LETTERS Saleh, A. A., Dionne, J. A. 2012; 12 (11): 5581-5586

  Abstract

  Optical trapping using focused laser beams has emerged as a powerful tool in the biological and physical sciences. However, scaling this technique to nanosized objects remains challenging due to the diffraction limit of light and the high power levels required for nanoscale trapping. In this paper, we propose plasmonic coaxial apertures as low-power optical traps for nanosized specimens. The illumination of a coaxial aperture with a linearly polarized plane wave generates a dual optical trapping potential well. We theoretically show that this potential can stably trap dielectric particles smaller than 10 nm in diameter while keeping the trapping power level below 20 mW. By tapering the thickness of the coaxial dielectric channel, trapping can be extended to sub-2-nm particles. The proposed structures may enable optical trapping and manipulation of dielectric particles ranging from single proteins to small molecules with sizes previously inaccessible.

  View details for DOI 10.1021/nl302627c

  View details for Web of Science ID 000311244400023

  View details for PubMedID 23035765

• Plasmonics: Metal-worthy methods and materials in nanophotonics MRS BULLETIN Dionne, J. A., Atwater, H. A. 2012; 37 (8): 717-724

  View details for DOI 10.1557/mrs.2012.171

  View details for Web of Science ID 000308083700008

• Plasmon nanoparticle superlattices as optical-frequency magnetic metamaterials OPTICS EXPRESS Alaeian, H., Dionne, J. A. 2012; 20 (14): 15781-15796

  Abstract

  Nanocrystal superlattices have emerged as a new platform for bottom-up metamaterial design, but their optical properties are largely unknown. Here, we investigate their emergent optical properties using a generalized semi-analytic, full-field solver based on rigorous coupled wave analysis. Attention is given to superlattices composed of noble metal and dielectric nanoparticles in unary and binary arrays. By varying the nanoparticle size, shape, separation, and lattice geometry, we demonstrate the broad tunability of superlattice optical properties. Superlattices composed of spherical or octahedral nanoparticles in cubic and AB(2) arrays exhibit magnetic permeabilities tunable between 0.2 and 1.7, despite having non-magnetic constituents. The retrieved optical parameters are nearly polarization and angle-independent over a broad range of incident angles. Accordingly, nanocrystal superlattices behave as isotropic bulk metamaterials. Their tunable permittivities, permeabilities, and emergent magnetism may enable new, bottom-up metamaterials and negative index materials at visible frequencies.

  View details for Web of Science ID 000306176100110

  View details for PubMedID 22772268

• Opportunities and Challenges of Using Plasmonic Components in Nanophotonic Architectures IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS Wassel, H. M., Dai, D., Tiwari, M., Valamehr, J. K., Theogarajan, L., Dionne, J., Chong, F. T., Sherwood, T. 2012; 2 (2): 154-168

  View details for DOI 10.1109/JETCAS.2012.2193934

  View details for Web of Science ID 000208972800004

• Quantum plasmon resonances of individual metallic nanoparticles NATURE Scholl, J. A., Koh, A. L., Dionne, J. A. 2012; 483 (7390): 421-U68

  Abstract

  The plasmon resonances of metallic nanoparticles have received considerable attention for their applications in nanophotonics, biology, sensing, spectroscopy and solar energy harvesting. Although thoroughly characterized for spheres larger than ten nanometres in diameter, the plasmonic properties of particles in the quantum size regime have been historically difficult to describe owing to weak optical scattering, metal-ligand interactions, and inhomogeneity in ensemble measurements. Such difficulties have precluded probing and controlling the plasmonic properties of quantum-sized particles in many natural and engineered processes, notably catalysis. Here we investigate the plasmon resonances of individual ligand-free silver nanoparticles using aberration-corrected transmission electron microscope (TEM) imaging and monochromated scanning TEM electron energy-loss spectroscopy (EELS). This technique allows direct correlation between a particle's geometry and its plasmon resonance. As the nanoparticle diameter decreases from 20 nanometres to less than two nanometres, the plasmon resonance shifts to higher energy by 0.5 electronvolts, a substantial deviation from classical predictions. We present an analytical quantum mechanical model that describes this shift due to a change in particle permittivity. Our results highlight the quantum plasmonic properties of small metallic nanospheres, with direct application to understanding and exploiting catalytically active and biologically relevant nanoparticles.

  View details for DOI 10.1038/nature10904

  View details for Web of Science ID 000301771200034

  View details for PubMedID 22437611

• Toward high-efficiency solar upconversion with plasmonic nanostructures JOURNAL OF OPTICS Atre, A. C., Garcia-Etxarri, A., Alaeian, H., Dionne, J. A. 2012; 14 (2)

  View details for DOI 10.1088/2040-8978/14/2/024008

  View details for Web of Science ID 000300303400009

• Optimized light absorption in Si wire array solar cells JOURNAL OF OPTICS Alaeian, H., Atre, A. C., Dionne, J. A. 2012; 14 (2)

  View details for DOI 10.1088/2040-8978/14/2/024006

  View details for Web of Science ID 000300303400007

• Waveguides with a silver lining: Low threshold gain and giant modal gain in active cylindrical and coaxial plasmonic devices PHYSICAL REVIEW B Saleh, A. A., Dionne, J. A. 2012; 85 (4)

  View details for DOI 10.1103/PhysRevB.85.045407

  View details for Web of Science ID 000298865200008

• Mirror, Mirror Physics 5 Dionne, J. 2012: 38
• Controlling the Interplay of Electric and Magnetic Modes via Fano-like Plasmon Resonances NANO LETTERS Sheikholeslami, S. N., Garcia-Etxarri, A., Dionne, J. A. 2011; 11 (9): 3927-3934

  Abstract

  Assemblies of strongly coupled plasmonic nanoparticles can support highly tunable electric and magnetic resonances in the visible spectrum. In this Letter, we theoretically demonstrate Fano-like interference effects between the fields radiated by the electric and magnetic modes of symmetric nanoparticle trimers. Breaking the symmetry of the trimer system leads to a strong interaction between the modes. The near and far-field electromagnetic properties of the broken symmetry trimer are tunable across a large spectral range. We exploit this Fano-like effect to demonstrate spatial and temporal control of the localized electromagnetic hotspots in the plasmonic trimer.

  View details for DOI 10.1021/nl202143j

  View details for Web of Science ID 000294790200072

  View details for PubMedID 21819059

• Realistic upconverter-enhanced solar cells with non-ideal absorption and recombination efficiencies JOURNAL OF APPLIED PHYSICS Atre, A. C., Dionne, J. A. 2011; 110 (3)

  View details for DOI 10.1063/1.3610522

  View details for Web of Science ID 000293956600144

• Giving photovoltaics the green light: Plasmon-enhanced upconversion for broadband solar absorption IEEE Photonics Conference (PHO) Dionne, J. A., Atre, A., Alaeian, H., Garcia, A. IEEE. 2011: 447–448

  View details for Web of Science ID 000299750700224

• Observations of shape-dependent hydrogen uptake trajectories from single nanocrystals JACS Communications Tang, M., L., Liu, N., Dionne, J., Alivisatos, A., P. 2011
• Si-based plasmonics for on-chip photonics invited review, Journal of Selected Topics in Quantum Electronics Dionne, J., Sweatlock, L., Sheldon, M., Alivisatos, A., P., Atwater, H. 2010; 16: 295
• PlasMOStor: a metal-oxide-silicon field-effect plasmonic modulator Nano Letters 9 Dionne, J., Diest, K., Sweatlock, L., Atwater, H. 2009: 897
• Flatland Photonics: Circumventing diffraction with planar plasmonic architectures Caltech Thesis Dionne, J. 2009
• Tunable color filters based on metal-insulator-metal resonators Nano Letters 9 Diest, K., Dionne, J., Spain, M., Atwater, H. 2009: 2579
• Are negative index materials achievable with surface plasmon waveguides? A case study of three plasmonic geometries Optics Express 16 Dionne, J., Verhagen, E., Polman, A., Atwater, H. 2008: 19001
• Near field visualization of strongly confined surface plasmon polaritons in metal-insulator-metal waveguides Nano Letters 8 Verhagen, E., Dionne, J., Kuipers, K., Atwater, H., Polman, A. 2008: 2925
• Silver diffusion bonding and layer transfer of lithium niobate to silver Applied Physics Letters 93 Diest, K., Archer, M., Dionne, J., Czubakowski, M., Atwater, H. 2008: 092906
• Negative refraction at visible frequencies Science 316 Lezec, H., Dionne, J., Atwater, H. 2007: 430
• Highly confined photon transport in subwavelength metallic slot waveguides NanoLetters 6 Dionne, J., Lezec, H., Atwater, H. 2006: 1928
• Plasmon slot waveguides: Towards chip-scale propagation with subwavelenth-scale localization Phys. Rev. B 73 Dionne, J., Sweatlock, L., Polman, A., Atwater, H. 2006: 035407
• Planar metal plasmon waveguides: frequency-dependent dispersion, propagation, localization, and loss beyond the free electron model Phys. Rev. B 72 Dionne, J., Sweatlock, L., Polman, A., Atwater, H. 2005: 075405
• The new ‘PN junction’: Plasmonics enables photonic access to the nanoworld MRS Bulletin Atwater, H., Maier, S., Polman, A., Dionne, J., Sweatlock, L. 2005: 30