Scholars@Duke
Henry Everitt

Henry Everitt

Adjunct Professor in the Department of Physics
Physics
heveritt@duke.edu
Box 90305, Durham, NC 27708-0305
Physics Bldg, Box 90305, Durham, NC 27708

Scholarly Works - Journal articles

Titanium Oxynitride by TiO2 Nitridation: A Comparative Study of Film, Nanoparticle, and Metasurface Nanostructure Properties

Journal article The Journal of Physical Chemistry C · August 27, 2026 AbstractTitanium oxynitride (TiOxNy) is a unique plasmonic material bridging dielectric TiO2 and metallic TiN. In this study, the properties of TiOxNy films, film-derived metasurfaces, and colloidal nanop ... Full text Cite

How resonator design improves performance of quantum cascade laser-pumped molecular lasers.

Journal article Optics express · July 2026 The widespread application of terahertz (THz) technology remains limited by the need for compact, room-temperature, high-power sources. The quantum cascade laser (QCL) pumped molecular laser (QPML) is what we feel is a promising new THz source with great t ... Full text Cite

Effect of gas exposure on GaN surface quantum wells

Journal article Applied Physics Letters · June 8, 2026 Some HEMT transistors and a variety of gas, pH, and molecular sensors use thin GaN capping layers that behave as surface quantum wells (SuQWs), such as those formed by a thin GaN layer with vacuum or gas on one side and a higher bandgap (Al0.2Ga ... Full text Cite

Quantum Semiconductor Heterostructures for meV Axion Dark Matter Detection.

Journal article Physical review letters · June 2026 We propose a novel strategy and a new class of detectors for the direct detection of axion dark matter in the meV mass range, based on resonantly enhanced axion-photon conversion through the inverse Primakoff effect in engineered radiometers composed of qu ... Full text Cite

Optimizing Plasmonic Photocatalysis by Controlling the Temporal Distribution of Incident Photons

Journal article ACS Catalysis · May 15, 2026 Of central interest in plasmonic photocatalysis is efficiency, defined as the ratio of the rate of chemical transformation to the power of the incident light. Efforts to enhance efficiency have focused largely on optimizing the photocatalyst structure and ... Full text Cite

Topology-optimized distributed 3d anisotropic Raman emission.

Journal article Optics express · March 2026 Topology optimization (TO) of 3d surface-enhanced Raman scattering (SERS) substrates faces challenges in managing field singularities and modeling orientation-averaged anisotropic molecules. We present 3d TO for manufacturable SERS substrates maximizing sp ... Full text Cite

Terahertz chiral optics with ordered carbon nanotube architectures

Journal article Newton · January 1, 2026 Chiral optical terahertz (THz) devices have significant technological implications for telecommunications, spectroscopy, and sensing. Engineering tunable, broadband, and cost-effective THz chiral materials has long been recognized as a challenging endeavor ... Full text Cite

Surface treatments affect GaN surface quantum well emission

Journal article Applied Physics Letters · October 13, 2025 Surface quantum wells (SuQWs), comprised of a thin layer of lower bandgap semiconductor sandwiched between a vacuum or air interface and a higher bandgap semiconductor, are sensitive to surface adsorbents that enhance or diminish surface recombination velo ... Full text Cite

Tuning the Reactivity of Al@TiO<sub>2</sub> Antenna-Reactor Plasmonic Photocatalysts by Controlling Oxygen Vacancies.

Journal article Nano letters · September 2025 Oxygen vacancies on a metal oxide surface enhance its catalytic activity. Here we investigate the controlled introduction of oxygen vacancies on core-shell Al@TiO2 antenna-reactor nanoparticle photocatalysts. Thermal annealing in an H2 Full text Cite

Aluminum Nanocrystals Form Voids under Their Native Oxide.

Journal article Nano letters · August 2025 Aluminum, the most abundant metal in the earth's crust, is protected and stabilized by a native surface oxide layer. Once the oxide is breached, rapid oxidation can occur, igniting Al in particulate form. By slowly heating and cooling Al nanocrystals of we ... Full text Cite

How clearly can an infrared detector see through a hot window?

Journal article Applied Physics Letters · July 28, 2025 At elevated temperatures, the self-emission from an infrared (IR) window may prevent a detector from seeing through it. Window coatings may be designed to maximize transmitted signal and minimize thermal self-emission noise toward the detector at a given t ... Full text Cite

The carbonyl sulfide terahertz laser and the effects of pump saturation

Journal article APL Photonics · June 1, 2025 Quantum cascade laser pumped molecular lasers (QPMLs) are capable of widely tunable emissions ranging from 0.1 to almost 10 THz. The QPML concept allows almost any gas composed of molecules with non-zero electric dipole moments to serve as gain media, incl ... Full text Cite

Observation of the magnonic Dicke superradiant phase transition.

Journal article Science advances · April 2025 Two-level atoms ultrastrongly coupled with single-mode cavity photons are predicted to exhibit a quantum phase transition, entering a phase in which both the atomic polarization and the photonic field are finite even without external driving. However, this ... Full text Cite

Hybridized Soliton Lasing in Coupled Semiconductor Lasers.

Journal article Physical review letters · January 2025 Coupling is an essential mechanism that drives complexity in natural systems, transforming single, noninteracting elements into intricate networks with rich physical properties. Here, we demonstrate a chip-scale coupled laser system that exhibits complex o ... Full text Cite

Designing structures that maximize spatially averaged surface-enhanced Raman spectra: erratum

Journal article Optics Express · December 2, 2024 This erratum corrects a misstatement regarding the absence of non-integrable singularities in 2d distributed Raman sensing applications and a formula [Eq. (9)] for one case of Raman enhancement. These changes do not impact the ... Full text Cite

Thermal imaging through hot emissive windows.

Journal article Communications engineering · November 2024 It is not currently possible for an infrared camera to see through a hot window. The window's own blinding thermal emission prevents objects on the other side from being imaged. Here, we demonstrate a path to overcoming this challenge by coating a hot wind ... Full text Cite

Reduced-Dimensionality Al Nanocrystals: Nanowires, Nanobars, and Nanomoustaches.

Journal article Nano letters · June 2024 Aluminum nanocrystals created by catalyst-driven colloidal synthesis support excellent plasmonic properties, due to their high level of elemental purity, monocrystallinity, and controlled size and shape. Reduction in the rate of nanocrystal growth enables ... Full text Cite

Terahertz Cavity Magnon Polaritons

Journal article Advanced Optical Materials · April 4, 2024 Hybrid light–matter coupled states, or polaritons, in magnetic materials have attracted significant attention due to their potential for enabling novel applications in spintronics and quantum information processing. However, most magnon-polariton studies i ... Full text Cite

Tailoring the aluminum nanocrystal surface oxide for all-aluminum-based antenna-reactor plasmonic photocatalysts.

Journal article Proceedings of the National Academy of Sciences of the United States of America · March 2024 Aluminum nanocrystals (AlNCs) are of increasing interest as sustainable, earth-abundant nanoparticles for visible wavelength plasmonics and as versatile nanoantennas for energy-efficient plasmonic photocatalysis. Here, we show that annealing AlNCs under va ... Full text Cite

Controlling product selectivity in hybrid gas/liquid reactors using gas conditions, voltage, and temperature.

Journal article Nanoscale · June 2023 For the conversion of CO2 into fuels and chemical feedstocks, hybrid gas/liquid-fed electrochemical flow reactors provide advantages in selectivity and production rates over traditional liquid phase reactors. However, fundamental questions remai ... Full text Cite

Exceptional point based lattice gyroscopes

Journal article Optical Materials Express · June 1, 2023 Ring laser gyroscopes (RLGs) based on non-Hermitian exceptional points (EPs) have garnered much recent interest due to their exceptional sensitivity. Such gyroscopes typically consist of two-ring laser resonators, one with loss and one with an equal amount ... Full text Cite

Non-Hermitian optics and photonics: introduction to the special issue

Journal article Optical Materials Express · June 1, 2023 This is an introduction to the feature issue of Optical Materials Express on Non-Hermitian Optics and Photonics. ... Full text Cite

d-Band Hole Dynamics in Gold Nanoparticles Measured with Time-Resolved Emission Upconversion Microscopy.

Journal article Nano letters · April 2023 The performance of photocatalysts and photovoltaic devices can be enhanced by energetic charge carriers produced from plasmon decay, and the lifetime of these energetic carriers greatly affects overall efficiencies. Although hot electron lifetimes in plasm ... Full text Cite

Designing structures that maximize spatially averaged surface-enhanced Raman spectra.

Journal article Optics express · January 2023 We present a general framework for inverse design of nanopatterned surfaces that maximize spatially averaged surface-enhanced Raman (SERS) spectra from molecules distributed randomly throughout a material or fluid, building upon a recently proposed trace f ... Full text Cite

Accurately Measuring Molecular Rotational Spectra in Excited Vibrational Modes.

Journal article Applied spectroscopy · December 2022 Although gas phase rotational spectroscopy is a mature field for which millions of rotational spectral lines have been measured in hundreds of molecules with sub-MHz accuracy, it remains a challenge to measure these rotational spectra in excited vibrationa ... Full text Cite

Direct H2S Decomposition by Plasmonic Photocatalysis: Efficient Remediation plus Sustainable Hydrogen Production

Journal article ACS Energy Letters · October 14, 2022 Plasmonic metal nanostructures have garnered rapidly increasing interest as heterogeneous photocatalysts, facilitating chemical bond activation and overcoming the high energy demands of conventional thermal catalysis. Here we report the highly efficient pl ... Full text Cite

Selective Photodetoxification of a Sulfur Mustard Simulant Using Plasmonic Aluminum Nanoparticles.

Journal article Nano letters · September 2022 Plasmonic nanostructures have attracted increasing interest in the fields of photochemistry and photocatalysis for their ability to enhance reactivity and tune reaction selectivity, a benefit of their strong interactions with light and their multiple energ ... Full text Cite

Effect of Humidity on C1, C2Product Selectivity for CO2Reduction in a Hybrid Gas/Liquid Electrochemical Reactor

Journal article ACS Applied Energy Materials · August 22, 2022 Hybrid gas/liquid-fed electrochemical flow reactors may become attractive alternatives for chemical synthesis once it is understood how catalytic product selectivity may be optimized through the control of gas phase reactants. Using a constant pH basic ele ... Full text Cite

Al@TiO2 Core-Shell Nanoparticles for Plasmonic Photocatalysis.

Journal article ACS nano · April 2022 Plasmon-induced photocatalysis is a topic of rapidly increasing interest, due to its potential for substantially lowering reaction barriers and temperatures and for increasing the selectivity of chemical reactions. Of particular interest for plasmonic phot ... Full text Cite

Multi-line lasing in the broadly tunable ammonia quantum cascade laser pumped molecular laser

Journal article Applied Physics Letters · February 21, 2022 Gaseous ammonia has previously been demonstrated as a compelling gain medium for a quantum cascade laser pumped molecular laser (QPML) exhibiting good power efficiency. Here, we explore the potential of the ammonia QPML to produce powerful, broadly tunable ... Full text Cite

Non-Hermitian metasurface with non-trivial topology.

Journal article Nanophotonics (Berlin, Germany) · February 2022 The synergy between topology and non-Hermiticity in photonics holds immense potential for next-generation optical devices that are robust against defects. However, most demonstrations of non-Hermitian and topological photonics have been limited to super-wa ... Full text Cite

A quantum cascade laser-pumped molecular laser tunable over 1 THz

Journal article APL Photonics · January 1, 2022 Despite decades of research, no frequency tunable sources span the terahertz gap between 0.3 and 3 THz. By introducing methyl fluoride (CH3F) as a new gain medium for a quantum cascade laser-pumped molecular laser (QPML), we demonstrate continuo ... Full text Cite

Mapping active strain using terahertz metamaterial laminates

Journal article APL Photonics · November 1, 2021 The ability to image strain fields in composite materials is an indispensable necessity for structural health monitoring. Embedded electromagnetic metamaterials sensitive to applied stresses and operating in the terahertz regime have been proposed as a sol ... Full text Cite

Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

Journal article Physical Review Applied · August 1, 2021 Quantum-cascade-laser-(QCL) pumped molecular lasers (QPMLs) have recently been introduced as a source of powerful (>1 mW) tunable (>1 THz) narrow-band (<10 kHz) continuous-wave terahertz radiation. The performance of these lasers depends critically on mole ... Full text Cite

Synergy between thermal and nonthermal effects in plasmonic photocatalysis

Journal article Nano Research · May 1, 2020 Plasmonic photocatalysis represents the synergetic union of two active fields of research: plasmonic effects in illuminated metallic nanoparticles and catalytic effects in tailored metallic nanoparticles. Traditionally, metallic nanoparticles that excel fo ... Full text Cite

Nanoplasmonic Photothermal Heating and Near-Field Enhancements: A Comparative Survey of 19 Metals

Journal article Journal of Physical Chemistry C · April 2, 2020 Localized surface plasmon resonances optically excited in metallic nanoparticles (NPs) produce beneficial thermal and nonthermal effects. Nonthermal effects, such as enhancing and localizing fields on subwavelength scales and photo-generating hot carriers, ... Full text Cite

Terahertz digital holographic imaging

Journal article Advances in Optics and Photonics · March 31, 2020 This tutorial describes the application of digital holography to the terahertz spectral region and demonstrates how to reconstruct images of complex dielectric targets. Using highly coherent terahertz sources, high-fidelity amplitude and phase reconstructi ... Full text Cite

Enlightening force chains: a review of photoelasticimetry in granular matter

Journal article Granular Matter · November 1, 2019 A photoelastic material will reveal its internal stresses when observed through polarizing filters. This eye-catching property has enlightened our understanding of granular materials for over half a century, whether in the service of art, education, or sci ... Full text Cite

Widely tunable compact terahertz gas lasers.

Journal article Science (New York, N.Y.) · November 2019 The terahertz region of the electromagnetic spectrum has been the least utilized owing to inadequacies of available sources. We introduce a compact, widely frequency-tunable, extremely bright source of terahertz radiation: a gas-phase molecular laser based ... Full text Cite

Confirming nonthermal plasmonic effects enhance CO2 methanation on Rh/TiO2 catalysts

Journal article Nano Research · August 1, 2019 In some cases, illumination of traditional thermal catalysts and tailored plasmonic photocatalysts may synergistically combine thermal and nonthermal mechanisms to enhance reaction rates and improve product selectivity at reduced temperatures. To understan ... Full text Cite

Gallium Polymorphs: Phase-Dependent Plasmonics

Journal article Advanced Optical Materials · July 4, 2019 Interest in gallium (Ga) is growing rapidly, thanks in part to its wide spectral tunability and its intriguing temperature-dependent polymorphism. In order to exploit and control phase-change plasmonics in the liquid and solid phases of Ga, an accurate und ... Full text Cite

Plasmonic nanoparticle-based epoxy photocuring: A deeper look

Journal article Materials Today · July 1, 2019 Many epoxy adhesives require high temperatures to bond composite materials. However, oven heating severely restricts what may be attached or enclosed within composite material-based structures and greatly limits the possibilities for repair. Inspired by in ... Full text Cite

Al doping in ZnO nanowires enhances ultraviolet emission and suppresses broad defect emission

Journal article Journal of Luminescence · July 1, 2019 The effect of Al doping on the nature of ultraviolet (UV) near band edge emission and broadband “green” visible emission from deep defects in ZnO nanowires is explored by temperature- and excitation intensity-dependent photoluminescence (PL) spectroscopy. ... Full text Cite

Light-Driven Chemical Looping for Ammonia Synthesis

Journal article ACS Energy Letters · May 31, 2019 Synthetic ammonia has been the primary worldwide source of agricultural fertilizer over the last century and is a promising carbon-free energy carrier for sustainable transportation. Despite its global importance, synthetic ammonia produced with the Haber- ... Full text Cite

Strain Sensing with Metamaterial Composites

Journal article Advanced Optical Materials · May 3, 2019 Mapping strain fields in visually opaque structural composites—for which failure is often sudden, irreparable, and even catastrophic—requires techniques to locate and record regions of stress, fatigue, and incipient failure. Many composite materials are tr ... Full text Cite

Quantitative analysis of gas phase molecular constituents using frequency-modulated rotational spectroscopy.

Journal article The Review of scientific instruments · May 2019 Rotational spectroscopy has been used for decades for virtually unambiguous identification of gas phase molecular species, but it has rarely been used for the quantitative analysis of molecular concentrations. Challenges have included the nontrivial recons ... Full text Cite

Light-Induced Thermal Gradients in Ruthenium Catalysts Significantly Enhance Ammonia Production.

Journal article Nano letters · March 2019 Industrial scale catalytic chemical synthesis demands both high reaction rates and high product yields. In exothermic chemical reactions, these conflicting objectives require a complex balance of optimized catalysts, high temperatures, high pressures, and ... Full text Cite

Cyclotron resonance in the high mobility GaAs/AlGaAs 2D electron system over the microwave, mm-wave, and terahertz- bands.

Journal article Scientific reports · February 2019 The reflected microwave power from the photo-excited high mobility GaAs/AlGaAs 2D device has been measured over the wide frequency band spanning from 30 to 330 GHz simultaneously along with diagonal magnetoresistance as a function of the magnetic field. Ea ... Full text Cite

Dielectric function and plasmonic behavior of Ga(II) and Ga(III)

Journal article Optical Materials Express · January 1, 2019 In order to exploit gallium's (Ga) rich polymorphism in the design of phase-change plasmonic systems, accurate understanding of the dielectric function of the different Ga-phases is crucial. The dielectric dispersion profiles of those phases appearing at a ... Full text Cite

Monitoring Chemical Reactions with Terahertz Rotational Spectroscopy

Journal article ACS Photonics · August 15, 2018 Rotational spectroscopy is introduced as a new in situ method for monitoring gas-phase reactants and products during chemical reactions. Exploiting its unambiguous molecular recognition specificity and extraordinary detection sensitivity, rotational spectr ... Full text Cite

A high-efficiency regime for gas-phase terahertz lasers.

Journal article Proceedings of the National Academy of Sciences of the United States of America · June 2018 We present both an innovative theoretical model and an experimental validation of a molecular gas optically pumped far-infrared (OPFIR) laser at 0.25 THz that exhibits 10× greater efficiency (39% of the Manley-Rowe limit) and 1,000× smaller volume than com ... Full text Cite

Plasmon-Enhanced Catalysis: Distinguishing Thermal and Nonthermal Effects.

Journal article Nano letters · March 2018 In plasmon-enhanced heterogeneous catalysis, illumination accelerates reaction rates by generating hot carriers and hot surfaces in the constituent nanostructured metals. In order to understand how photogenerated carriers enhance the nonthermal reaction ra ... Full text Cite

The UV Plasmonic Behavior of Distorted Rhodium Nanocubes.

Journal article Nanomaterials (Basel, Switzerland) · December 2017 For applications of surface-enhanced spectroscopy and photocatalysis, the ultraviolet (UV) plasmonic behavior and charge distribution within rhodium nanocubes is explored by a detailed numerical analysis. The strongest plasmonic hot-spots and charge concen ... Full text Cite

Characterization of an active metasurface using terahertz ellipsometry

Journal article Applied Physics Letters · November 6, 2017 Switchable metasurfaces fabricated on a doped epi-layer have become an important platform for developing techniques to control terahertz (THz) radiation, as a DC bias can modulate the transmission characteristics of the metasurface. To model and understand ... Full text Cite

Millimeter Wave and Terahertz Synthetic Aperture Radar for Locating Metallic Scatterers Embedded in Scattering Media

Journal article IEEE Transactions on Terahertz Science and Technology · November 1, 2017 A rail-mounted synthetic aperture radar has been constructed to operate at W-band (75-110 GHz) and a terahertz (THz) band (325-500 GHz) in order to ascertain its ability to detect and locate isolated small, visually obscured metallic scatterers embedded in ... Full text Cite

Narrowband Metamaterial Absorber for Terahertz Secure Labeling

Journal article Journal of Infrared Millimeter and Terahertz Waves · September 1, 2017 Flexible metamaterial films, fabricated by photolithography on a thin copper-backed polyimide substrate, are used to mark or barcode objects securely. The films are characterized by continuous-wave terahertz spectroscopic ellipsometry and visualized by a s ... Full text Cite

Wide bandwidth, millimeter-resolution inverse synthetic aperture radar imaging.

Journal article Journal of the Optical Society of America. A, Optics, image science, and vision · July 2017 The combination of wide bandwidth W-band inverse synthetic aperture radar imagery and high-fidelity numerical simulations has been used to identify distinguishing signatures from simple metallic and dielectric targets. Targets are located with millimeter-s ... Full text Open Access Cite

Millimeter wave radiation-induced magnetoresistance oscillations in the high quality GaAs/AlGaAs 2D electron system under bichromatic excitation

Journal article Physical Review B · May 3, 2017 Millimeter wave radiation-induced magnetoresistance oscillations are examined in the GaAs/AlGaAs 2D electron system under bichromatic excitation in order to study the evolution of the oscillatory diagonal magnetoresistance, Rxx as the millimeter wave inten ... Full text Cite

UVB-emitting InAlGaN multiple quantum well synthesized using plasma-assisted molecular beam epitaxy

Journal article Aip Advances · March 1, 2017 A high Al-content (y > 0.4) multi-quantum-well (MQW) structure with a quaternary InxAlyGa(1-x-y)N active layer was synthesized using plasma-assisted molecular beam epitaxy. The MQW structure exhibits strong carrier confinem ... Full text Cite

Compressive sensing and adaptive sampling applied to millimeter wave inverse synthetic aperture imaging.

Journal article Optics express · February 2017 In order to improve speed and efficiency over traditional scanning methods, a Bayesian compressive sensing algorithm using adaptive spatial sampling is developed for single detector millimeter wave synthetic aperture imaging. The application of this algori ... Full text Open Access Cite

Light-driven reaction converts carbon-dioxide into fuel

Journal article Chemical Engineering World · February 1, 2017 Duke University researchers have developed tiny nanoparticies that help convert carbon dioxide into methane using only ultraviolet light as an energy source. In the past two decades, scientists have explored new and useful ways that light can be used to ad ... Cite

How sulfidation of ZnO powders enhances visible fluorescence

Journal article Journal of Materials Chemistry C · January 1, 2017 The mechanism for producing efficient white light phosphors from sulfidated zinc oxide (ZnO) powders is elucidated. ZnO powders prepared by vacuum annealing produce powders of oxygen-deficient ZnO:Zn, while ZnO powders annealed in a sulfur atmosphere produ ... Full text Cite

How an oxide shell affects the ultraviolet plasmonic behavior of Ga, Mg, and Al nanostructures.

Journal article Optics express · September 2016 The ultraviolet (UV) range presents new challenges for plasmonics, with interesting applications ranging from engineering to biology. In previous research, gallium, aluminum, and magnesium were found to be very promising UV plasmonic metals. However, a nat ... Full text Open Access Cite

Photoluminescence Mechanism and Photocatalytic Activity of Organic-Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration.

Journal article Langmuir : the ACS journal of surfaces and colloids · May 2016 Organic-inorganic hybrid materials formed by sequential vapor infiltration (SVI) of trimethylaluminum into polyester fibers are demonstrated, and the photoluminescence of the fibers is evaluated using a combined UV-vis and photoluminescence excitation (PLE ... Full text Open Access Cite

Carbon nanotube fiber terahertz polarizer

Journal article Applied Physics Letters · April 4, 2016 Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a sim ... Full text Cite

Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.

Journal article ACS nano · April 2016 The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkab ... Full text Open Access Cite

How Annealing and Charge Scavengers Affect Visible Emission from ZnO Nanocrystals

Journal article Journal of Physical Chemistry C · March 17, 2016 Simultaneous transmission infrared (IR) absorption and photoluminescence (PL) spectroscopies are used to reveal the correlation of free electron and defect densities during the stepwise annealing of ZnO nanocrystals in high vacuum. For increasing annealing ... Full text Open Access Cite

Global k -space analysis of electron-phonon interaction in graphene and application to M -point spectroscopy

Journal article Physical Review B · February 8, 2016 Recently, optical probes have become available that can access and observe energy renormalization due to electron-phonon interaction in graphene away from the well-studied Dirac K point. Using an expanded deformation potential approach, we present a theore ... Full text Open Access Cite

Aluminum Nanocrystals as a Plasmonic Photocatalyst for Hydrogen Dissociation.

Journal article Nano letters · February 2016 Hydrogen dissociation is a critical step in many hydrogenation reactions central to industrial chemical production and pollutant removal. This step typically utilizes the favorable band structure of precious metal catalysts like platinum and palladium to a ... Full text Cite

Size-tunable rhodium nanostructures for wavelength-tunable ultraviolet plasmonics.

Journal article Nanoscale horizons · January 2016 Polydisperse rhodium nanoparticles have recently shown promise for ultraviolet (UV) plasmonics, but controlling the size and morphology of metal nanoparticles is essential for tuning surface plasmon resonances. Here we report the use of slow-injection poly ... Full text Cite

Fano Resonant Aluminum Nanoclusters for Plasmonic Colorimetric Sensing.

Journal article ACS nano · November 2015 Aluminum is an abundant and high-quality material for plasmonics with potential for large-area, low-cost photonic technologies. Here we examine aluminum nanoclusters with plasmonic Fano resonances that can be tuned from the near-UV into the visible region ... Full text Cite

Room temperature Ultraviolet B emission from InAlGaN films synthesized by plasma-assisted molecular beam epitaxy

Journal article Applied Physics Letters · September 28, 2015 Thin films of the wide bandgap quaternary semiconductor InxAlyGa(1-x-y)N with low In (x=0.01-0.05) and high Al composition (y=0.40-0.49) were synthesized on GaN templates by plasma-assisted molecular beam epitaxy. High-reso ... Full text Cite

Rhodium Tripod Stars for UV Plasmonics

Journal article Journal of Physical Chemistry C · June 4, 2015 Local field enhancements produced by metal nanoparticles have been widely investigated in the visible range for common metals like gold and silver, but recent interest in ultraviolet plasmonics has required consideration of alternate metals. Aluminum and g ... Full text Cite

Aluminum nanocrystals.

Journal article Nano letters · April 2015 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, icos ... Full text Cite

Rhodium nanoparticles for ultraviolet plasmonics.

Journal article Nano letters · February 2015 The nonoxidizing catalytic noble metal rhodium is introduced for ultraviolet plasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified polyol reduction method, have a calculated local surface plasmon resonance near 330 nm. By attaching ... Full text Open Access Cite

Gallium plasmonics: deep subwavelength spectroscopic imaging of single and interacting gallium nanoparticles.

Journal article ACS nano · February 2015 Gallium has recently been demonstrated as a phase-change plasmonic material offering UV tunability, facile synthesis, and a remarkable stability due to its thin, self-terminating native oxide. However, the dense irregular nanoparticle (NP) ensembles fabric ... Full text Open Access Cite

Terahertz digital holographic imaging of voids within visibly opaque dielectrics

Journal article IEEE Transactions on Terahertz Science and Technology · January 1, 2015 Terahertz digital off-axis holography (THzDH) has been demonstrated as a non-destructive tool for imaging voids within visually opaque dielectrics. Using a raster scanning heterodyne detector, the imager captures lensless transmission holograms formed by t ... Full text Open Access Cite

Design and signature analysis of remote trace-gas identification methodology based on infrared-terahertz double-resonance spectroscopy

Journal article Physical Review Applied · November 26, 2014 The practicality of a newly proposed infrared-terahertz (IR-THz) double-resonance (DR) spectroscopic technique for remote trace-gas identification is explored. The strength of the DR signatures depends on known molecular parameters from which a combination ... Full text Open Access Cite

Formation of novel photoluminescent hybrid materials by sequential vapor infiltration into polyethylene terephthalate fibers

Journal article Journal of Materials Research · November 12, 2014 Fibrous polyethylene terephthalate (PET) was modified by organometallic vapor exposure to form hybrid materials with unique photoluminescent characteristics. Using a sequential vapor infiltration (SVI) process, the elongated exposures of trimethylaluminum ... Full text Cite

Room temperature photoluminescence from InxAl(1-x)N films deposited by plasma-assisted molecular beam epitaxy

Journal article Applied Physics Letters · September 29, 2014 InAlN films deposited by plasma-assisted molecular beam epitaxy exhibited a lateral composition modulation characterized by 10-12 nm diameter, honeycomb-shaped, columnar domains with Al-rich cores and In-rich boundaries. To ascertain the effect of this mic ... Full text Open Access Cite

Ultraviolet-Visible Plasmonic Properties of Gallium Nanoparticles Investigated by Variable-Angle Spectroscopic and Mueller Matrix Ellipsometry

Journal article ACS Photonics · July 16, 2014 Self-assembled, irregular ensembles of hemispherical Ga nanoparticles (NPs) were deposited on sapphire by molecular beam epitaxy. These samples, whose constituent unimodal or bimodal distribution of NP sizes was controlled by deposition time, exhibited loc ... Full text Open Access Cite

Adaptive millimeter-wave synthetic aperture imaging for compressive sampling of sparse scenes.

Journal article Optics express · June 2014 We apply adaptive sensing techniques to the problem of locating sparse metallic scatterers using high-resolution, frequency modulated continuous wave W-band RADAR. Using a single detector, a frequency stepped source, and a lateral translation stage, invers ... Full text Open Access Cite

Optical characterization of electron-phonon interactions at the saddle point in graphene.

Journal article Physical review letters · May 2014 The role of many-body interactions is experimentally and theoretically investigated near the saddle point absorption peak of graphene. The time and energy-resolved differential optical transmission measurements reveal the dominant role played by electron-a ... Full text Open Access Cite

Metals for UV plasmonics

Journal article Optics InfoBase Conference Papers · January 1, 2014 Electromagnetic enhancement of metallic nanoparticles on substrates is assessed by an exhaustive numerical analysis. The potential of each technologically promising metal for UVplasmonic applications may be ascertained.© OSA 2014. ... Cite

Effect of pressure and Al doping on structural and optical properties of ZnO nanowires synthesized by chemical vapor deposition

Journal article Journal of Luminescence · January 1, 2014 The effect of Al doping concentration and oxygen ambient pressure on the structural and optical properties of chemical vapor deposition-grown, Al-doped ZnO nanowires is studied. As Al doping increases, the strength of the broad visible emission band decrea ... Full text Open Access Cite

Aluminum for plasmonics.

Journal article ACS nano · January 2014 Unlike silver and gold, aluminum has material properties that enable strong plasmon resonances spanning much of the visible region of the spectrum and into the ultraviolet. This extended response, combined with its natural abundance, low cost, and amenabil ... Full text Open Access Cite

Saga of efficiency degradation at high injection in InGaN light emitting diodes

Journal article Turkish Journal of Physics · January 1, 2014 What has turned into highly complex and somewhat misunderstood efficiency loss mechanisms occurring in light-emitting diodes (LEDs) based on the InN-GaN material system at high injection levels are discussed. Suggestions are made as to the dominant mechani ... Full text Cite

The dependence of ZnO photoluminescence efficiency on excitation conditions and defect densities

Journal article Applied Physics Letters · November 11, 2013 The quantum efficiencies of both the band edge and deep-level defect emission from annealed ZnO powders were measured as a function of excitation fluence and wavelength from a tunable sub-picosecond source. A simple model of excitonic decay reproduces the ... Full text Cite

Spectroscopic investigation of coupling among asymmetric InGaN/GaN multiple quantum wells grown on non-polar a-plane GaN substrates

Journal article Applied Physics Letters · October 28, 2013 Low defect density asymmetric multiple quantum wells (MQWs) of InGaN/GaN grown on non-polar a-plane GaN substrates were investigated using time-integrated and time-resolved photoluminescence spectroscopy. Comparison of these spectra with the predicted emis ... Full text Open Access Cite

UV plasmonic behavior of various metal nanoparticles in the near- and far-field regimes: Geometry and substrate effects

Journal article Journal of Physical Chemistry C · September 26, 2013 The practical efficacy of technologically promising metals for use in ultraviolet plasmonics (3-6 eV) is assessed by an exhaustive numerical analysis. This begins with estimates of the near- and far-field electromagnetic enhancement factors of isolated hem ... Full text Cite

Terahertz photovoltaic detection of cyclotron resonance in the regime of radiation-induced magnetoresistance oscillations

Journal article Physical Review B Condensed Matter and Materials Physics · June 17, 2013 We examine and compare the diagonal magnetoresistance, Rxx, and the photovoltage induced by microwave (42≤f<300 GHz) and terahertz (f≥300 GHz) photoexcitation in the high mobility quasi-two-dimensional GaAs/AlGaAs system. The data demonstrate st ... Full text Open Access Cite

Ultraviolet nanoplasmonics: a demonstration of surface-enhanced Raman spectroscopy, fluorescence, and photodegradation using gallium nanoparticles.

Journal article Nano letters · June 2013 Self-assembled arrays of hemispherical gallium nanoparticles deposited by molecular beam epitaxy on a sapphire support are explored as a new type of substrate for ultraviolet plasmonics. Spin-casting a 5 nm film of crystal violet upon these nanoparticles p ... Full text Cite

Shallow acceptor complexes in p-type ZnO

Journal article Applied Physics Letters · April 15, 2013 We show that N-doped ZnO films grown on sapphire can exhibit significant (∼1018 cm-3) room-temperature p-type behavior when sufficient nitrogen (N) is incorporated and the material is annealed appropriately. Substitutional N on the ox ... Full text Cite

Localized excitons mediate defect emission in ZnO powders

Journal article Journal of Applied Physics · April 7, 2013 A series of continuous-wave spectroscopic measurements elucidates the mechanism responsible for the technologically important green emission from deep-level traps in ZnO:Zn powders. Analysis of low-temperature photoluminescence (PL) and PL excitation spect ... Full text Cite

Adaptive scanning for synthetic aperture imagers

Journal article Optics InfoBase Conference Papers · January 1, 2013 Synthetic aperture imagers measure the space-bandwidth product of full-apertures by moving a single detector. We show results from an adaptive sensing experiment that demonstrate a three times speedup over full-scans. © 2013 Optical Society of America. ... Cite

Aluminum plasmonic nanoantennas.

Journal article Nano letters · November 2012 The use of aluminum for plasmonic nanostructures opens up new possibilities, such as access to short-wavelength regions of the spectrum, complementary metal-oxide-semiconductor (CMOS) compatibility, and the possibility of low-cost, sustainable, mass-produc ... Full text Cite

Infrared-terahertz double-resonance spectroscopy of CH 3F and CH 3Cl at atmospheric pressure

Journal article Physical Review A Atomic Molecular and Optical Physics · May 16, 2012 A method for highly selective remote sensing of atmospheric trace polar molecular gases is described. Based on infrared-terahertz double-resonance spectroscopic techniques, the molecule-specific coincidence between the lines of a CO 2 laser and ... Full text Cite

Terahertz interferometric synthetic aperture tomography for confocal imaging systems.

Journal article Optics letters · April 2012 Terahertz (THz) interferometric synthetic aperture tomography (TISAT) for confocal imaging within extended objects is demonstrated by combining attributes of synthetic aperture radar and optical coherence tomography. Algorithms recently devised for interfe ... Full text Cite

Ultraviolet surface-enhanced Raman scattering at the plasmonic band edge of a metallic grating.

Journal article Optics express · January 2012 Surface-enhanced Raman Scattering (SERS) is studied in sub-wavelength metallic gratings on a substrate using a rigorous electromagnetic approach. In the ultraviolet SERS is limited by the metallic dampening, yet enhancements as large as 10(5) are predicted ... Full text Cite

Sulfur-doped zinc oxide (ZnO) Nanostars: Synthesis and simulation of growth mechanism

Journal article Nano Research · 2012 We present a bottom-up synthesis, spectroscopic characterization, and ab initio simulations of star-shaped hexagonal zinc oxide (ZnO) nanowires. The ZnO nanostructures were synthesized by a low-temperature hydrothermal growth method. The cross-section of t ... Full text Cite

Shape matters: plasmonic nanoparticle shape enhances interaction with dielectric substrate.

Journal article Nano letters · September 2011 Numerical analyses of the ultraviolet and visible plasmonic spectra measured from hemispherical gallium nanostructures on dielectric substrates reveal that resonance frequencies are quite sensitive to illumination angle and polarization in a way that depen ... Full text Cite

Nanotechnology research and development for military and industrial applications

Journal article Proceedings of SPIE the International Society for Optical Engineering · May 23, 2011 Researchers at the Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) have initiated multidiscipline efforts to develop nano-based structures and components for insertion into advanced missile, aviation, and autonomous air and ... Full text Cite

Terahertz digital holography using angular spectrum and dual wavelength reconstruction methods.

Journal article Optics express · May 2011 Terahertz digital off-axis holography is demonstrated using a Mach-Zehnder interferometer with a highly coherent, frequency tunable, continuous wave terahertz source emitting around 0.7 THz and a single, spatially-scanned Schottky diode detector. The recon ... Full text Cite

Spatio-temporal theory of lasing action in optically-pumped rotationally excited molecular gases.

Journal article Optics express · April 2011 We investigate laser emission from optically-pumped rotationally excited molecular gases confined in a metallic cavity. To this end, we have developed a theoretical framework able to accurately describe, both in the spatial and temporal domains, the molecu ... Full text Cite

Transmissive quasi-optical Ronchi phase grating for terahertz frequencies.

Journal article Optics letters · November 2010 A transmissive, square-wave Ronchi phase grating has been fabricated from the dielectric polytetrafluoroethylene to diffract an ~0.7 THz beam quasi-optically. When illuminated by a coherent, cw terahertz (THz) source, the spot separation of the ±1 diffract ... Full text Cite

Effect of oxygen pressure on the structure and luminescence of Eu-doped Gd 2O 3 thin films

Journal article Physica Status Solidi A Applications and Materials Science · August 1, 2010 Europium-doped gadolinium oxide (Gd2O3) thin films were deposited on sapphire substrates by pulsed laser deposition (PLD). The effect of oxygen pressure during deposition on the structure of the thin films, investigated by transmission electron microscopy ... Full text Cite

Spectra and energy levels of Eu3+ in cubic phase Gd2O3

Journal article Physica Status Solidi B Basic Research · July 1, 2010 In pulsed laser deposition of the sesquioxide semiconductor Gd2O3, adjusting the chamber oxygen pressure controls the crystalline structure of the host. This technique was used to deposit thin films of nominally 1.6% by weight europiu ... Full text Cite

Optimal composition of europium gallium oxide thin films for device applications

Journal article Journal of Applied Physics · May 15, 2010 Europium gallium oxide (Eux Ga1-x) 2 O3 thin films were deposited on sapphire substrates by pulsed laser deposition with varying Eu content from x=2.4 to 20 mol %. The optical and physical effects of high europiu ... Full text Open Access Cite

Effects of reabsorption and spatial trap distributions on the radiative quantum efficiencies of ZnO

Journal article Physical Review B Condensed Matter and Materials Physics · March 15, 2010 Ultrafast time-resolved photoluminescence spectroscopy following one- and two-photon excitations of ZnO powder is used to gain unprecedented insight into the surprisingly high external quantum efficiency of its "green" defect emission band. The role of exc ... Full text Open Access Cite

A double resonance approach to submillimeter/terahertz remote sensing at atmospheric pressure

Journal article IEEE Journal of Quantum Electronics · December 1, 2009 The remote sensing of gases in complex mixtures at atmospheric pressure is a challenging problem and much attention has been paid to it. The most fundamental difference between this application and highly successful astrophysical and upper atmospheric remo ... Full text Cite

Comparison of conjugated polymer deposition techniques by photoluminescence spectroscopy

Journal article Journal of Vacuum Science and Technology B · October 2009 The effects of various deposition techniques on the photoluminescence spectra of the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-(1-cyanovinylene) phenylene] (MEH-CN-PPV) are investigated. Photoluminescence spectroscopy provides insight to t ... Cite

Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles.

Journal article Journal of the American Chemical Society · September 2009 Size-controlled gallium nanoparticles deposited on sapphire were explored as alternative substrates to enhance Raman spectral signatures. Gallium's resilience following oxidation is inherently advantageous in comparison with silver for practical ex vacuo n ... Full text Cite

Retraction:Effect of the surface states on photoluminescence from surface GaN/Al 0.2Ga0.8N quantum wells

Journal article Epl · August 1, 2009 We report on photoluminescence (PL) measurements at 85 K for GaN/Al 0.2Ga0.8N surface quantum wells (SQWs) with a width in the range of 1.51-2.9 nm. The PL spectra show a redshift with decreasing SQW width, in contrast to the blueshif ... Full text Cite

Carrier dynamics and photoexcited emission efficiency of ZnO:Zn phosphor powders

Journal article Proceedings of SPIE the International Society for Optical Engineering · June 15, 2009 Nonstoichiometric ZnO with an excess of Zn atoms (ZnO:Zn) has a long history of use as a green/monochrome phosphor in electron-excited vacuum fluorescent and field emission displays. The advent of ultraviolet lasers and light emitting diodes presents the p ... Full text Cite

Direct and indirect photoluminescence excitation and ultraviolet emission from Tm-doped AlxGa1-xN

Journal article Journal of Applied Physics · May 8, 2009 We provide experimental evidence for direct and indirect excitations of photoluminescence (PL) from Tm-doped AlxGa1-xN of varying Al content. Direct excitation of Tm3+ ions is observed primarily at 85 K through transitions ... Full text Cite

Diameter-controlled vapor-solid epitaxial growth and properties of aligned ZnO nanowire arrays

Journal article Journal of Physical Chemistry C · March 12, 2009 A facile, template-free method was used to grow large areas of well-aligned ZnO nanowire arrays on amorphous SiO 2 substrates. The arrays are composed of vertically aligned, single-crystalline, wurtzitic [001] ZnO nanowires whose diameters were ... Full text Cite

Effect of Tm3+ -induced defects on the photoexcitation energy relaxation in Tm-doped Alx Ga1-x N

Journal article Physical Review B Condensed Matter and Materials Physics · March 3, 2009 We provide evidence that the Tm3+ -induced defects in Tm-doped Alx Ga1-x N hosts play a major role in the nonradiative transfer of the excitation energy from the I1 6 state to the D1 2 state of Tm3+ ions from which the most efficient photoluminescence (PL) ... Full text Cite

Band bending and adsorption/desorption kinetics on N-polar GaN surfaces

Journal article Journal of Vacuum Science and Technology B Microelectronics and Nanometer Structures · February 17, 2009 Highly reactive N-polar [000-1] GaN surfaces were analyzed using spectroscopic ellipsometry. Following exposure to air, observed changes in the pseudodielectric function near the GaN band edge indicate that surface contamination reduces the band bending. A ... Full text Cite

Plasmonic Gallium Nanoparticles on Polar Semiconductors: Interplay between Nanoparticle Wetting, Localized Surface Plasmon Dynamics, and Interface Charge

Journal article Langmuir · January 2009 Ga nanoparticles supported on large band gap semiconductors like SiC, GaN, and ZnO are interesting for plasmon-enhanced UV-emitting solid-state devices. We investigate the influence of the polarity of the SiC, GaN, and ZnO wurtzite semiconductors on the we ... Cite

Indium adlayer kinetics on the gallium nitride (0001) surface: Monitoring indium segregation and precursor-mediated adsorption

Journal article Physical Review B Condensed Matter and Materials Physics · March 20, 2008 Indium kinetics and evidence for indium segregation on the GaN (0001) surface are investigated via in situ spectroscopic ellipsometry. Indium deposition exhibits two stable states at coverages of 1.0 and 1.7 ML within the temperature range of 630-688°C. Fo ... Full text Cite

Novel, real-time measurement of plasmon resonance - tailoring nanoparticle geometry optically

Journal article Optics Infobase Conference Papers · January 1, 2008 We demonstrate novel use of in situ spectroscopic ellipsometry to probe in real-time metal nanoparticle deposition. Real-time monitoring of NP assembly plasmon resonance enables control of NP size via the plasmon resonance and vice versa. © 2008 OSA. ... Cite

Novel, real-time measurement of plasmon resonance - tailoring nanoparticle geometry optically

Journal article Optics InfoBase Conference Papers · January 1, 2008 We demonstrate novel use of in situ spectroscopic ellipsometry to probe in real-time metal nanoparticle deposition. Real-time monitoring of NP assembly plasmon resonance enables control of NP size via the plasmon resonance and vice versa. ... Cite

Spectroscopic and energy transfer studies of Eu3+ centers in GaN

Journal article Journal of Applied Physics · October 22, 2007 Photoluminescence (PL), photoluminescence excitation (PLE), and time-resolved PL spectroscopies have been carried out at room temperature and 86 K on transitions from D25, D15, and D05 excited states to numerous FJ7 ground states of Eu-doped GaN films grow ... Full text Cite

Epitaxial lateral overgrowth of a -plane GaN by metalorganic chemical vapor deposition

Journal article Journal of Applied Physics · September 20, 2007 We report on epitaxial lateral overgrowth (ELO) of (11 2- 0) a -plane GaN by metalorganic chemical vapor deposition. Different growth rates of Ga- and N-polar wings together with wing tilt create a major obstacle for achieving a smooth, fully coalesced sur ... Full text Cite

Kinetics of gallium adlayer adsorption/desorption on polar and nonpolar GaN surfaces

Journal article Journal of Vacuum Science and Technology B Microelectronics and Nanometer Structures · June 11, 2007 Spectroscopic ellipsometry installed on a GEN-II plasma assisted molecular beam epitaxy machine has been shown to be an effective in situ real time tool for monitoring the kinetics of gallium adlayer adsorption/desorption on the GaN surface. In this work, ... Full text Cite

Low dislocation densities and long carrier lifetimes in GaN thin films grown on a Si Nx nanonetwork

Journal article Applied Physics Letters · February 5, 2007 Significant improvement of structural and optical qualities of GaN thin films on sapphire substrates was achieved by metal organic chemical vapor deposition with in situ Si Nx nanonetwork. Transmission electron microscope (TEM) studies revealed that screw- ... Full text Cite

Real-time plasmon resonance tuning of liquid Ga nanoparticles by in situ spectroscopic ellipsometry

Journal article Applied Physics Letters · 2007 Liquid Ga nanoparticles have been deposited on sapphire substrates at room temperature. The optical evolution of Ga nanoparticle surface plasmon resonance during deposition has been characterized by in situ real-time spectroscopic ellipsometry to control a ... Full text Link to item Cite

Photoluminescence study of ZnO films codoped with nitrogen and tellurium

Journal article Journal of Applied Physics · December 1, 2006 Epitaxial ZnO films codoped with tellurium and nitrogen were grown by pulsed laser deposition on c -axis oriented sapphire substrates. The codoping strategy allowed the resistivity of the films to be controlled over several orders of magnitude and may prov ... Full text Cite

Near-field scanning optical microscopy and time-resolved optical characterization of epitaxial lateral overgrown c-plane and a-plane GaN

Journal article Applied Physics Letters · December 1, 2006 Epitaxial lateral overgrowth (ELO) was employed for both c -plane and a -plane GaN layers on sapphire, and a more pronounced optical improvement was observed for the a -plane GaN as evidenced by the significantly increased band edge photoluminescence (PL). ... Full text Cite

Kinetics of gallium adsorption and desorption on (0001) gallium nitride surfaces

Journal article Applied Physics Letters · November 13, 2006 In situ spectroscopic ellipsometry kinetic characterization is used to monitor the behavior of Ga atoms during and after Ga flux impingement upon a (0001) GaN surface at various temperatures in the range of 680-750 °C. The observed saturation of the pseudo ... Full text Cite

Time-resolved investigation of bright visible wavelength luminescence from sulfur-doped ZnO nanowires and micropowders.

Journal article Nano letters · June 2006 Sulfur-doped zinc oxide (ZnO) nanowires grown on gold-coated silicon substrates inside a horizontal tube furnace exhibit remarkably strong visible wavelength emission with a quantum efficiency of 30%, an integrated intensity 1600 times stronger than band e ... Full text Cite

Optical characterization of Eu-doped Β-Ga 2O 3 thin films

Journal article Applied Physics Letters · May 29, 2006 Europium-doped Β- Ga2 O3 thin films were grown on double-side polished c -axis (0001) sapphire substrates by pulsed laser deposition at 850 °C. Transmission measurements of the films revealed a sharp band edge with a band gap at 5.0 eV. The films exhibited ... Full text Cite

Optical studies of carrier dynamics and non-equilibrium optical phonons in nitride-based wide bandgap semiconductors

Journal article Superlattices and Microstructures · August 1, 2005 Ultrafast optical probes, photoluminescence spectroscopy, and Raman spectroscopy have been applied to investigate carrier dynamics in nitride-based binary and ternary, and dilute nitride semiconductors. Carrier dynamics in the form of radiative and non-rad ... Full text Cite

Long carrier lifetimes in GaN epitaxial layers grown using TiN porous network templates

Journal article Applied Physics Letters · June 6, 2005 Improved structural quality and radiative efficiency were observed in GaN thin films grown by metalorganic chemical vapor deposition on TiN porous network templates formed by in situ thermal annealing of Ti in ammonia. The room-temperature decay times obta ... Full text Cite

Increased carrier lifetimes in GaN epitaxial films grown using SiN and TiN porous network layers

Journal article Journal of Applied Physics · May 15, 2005 Improved structural quality and radiative efficiency were observed in GaN thin films grown by metalorganic chemical vapor deposition on SiN and TiN porous network templates. The room-temperature decay times obtained from biexponential fits to time-resolved ... Full text Cite

Refractive indices of ZnSiN 2 on r-plane sapphire

Journal article Applied Physics Letters · March 21, 2005 II-IV- N2 wide band gap semiconductors such as ZnSi N2, ZnGe N2, and ZnSiGe N2 have potential uses for nonlinear materials and as lattice matching compounds for the growth of SiC and GaN devices. In this study, the dispersion of the TE and TM indices of re ... Full text Cite

Size dependence of carrier recombination efficiency in GaN quantum dots

Journal article IEEE Transactions on Nanotechnology · March 1, 2005 The dependence of radiative recombination rate and efficiency on GaN quantum-dot (QD) size and temperature is studied by time-resolved photoluminescence (PL) spectroscopy. The emission is dominated by radiative recombination at low temperatures (<125 K) an ... Full text Cite

Effect of optical excitation energy on the red luminescence of Eu3+ in GaN

Journal article Applied Physics Letters · January 31, 2005 Photoluminescence (PL) excitation spectroscopy mapped the photoexcitation wavelength dependence of the red luminescence (D05 → F27) from GaN:Eu. Time-resolved PL measurements revealed that for excitation at the GaN bound exciton energy, the decay transient ... Full text Cite

Bright, eye-matched visible emission from ZnO nanowires

Journal article Optics InfoBase Conference Papers · January 1, 2005 Broadband, visible-wavelength emission of unprecedented brightness from ZnO nanowires is characterized by steady-state and ultrafast time-resolved spectroscopy. Energy transfer is explored by simultaneously studying the unusually fast decay of band edge em ... Cite

Excitonic fine structure and recombination dynamics in single-crystalline ZnO

Journal article Physical Review B Condensed Matter and Materials Physics · November 1, 2004 The optical properties of a high quality bulk ZnO, thermally post treated in a forming gas environment are investigated by temperature dependent continuous wave and time-resolved photoluminescence (PL) measurements. Several bound and free exciton transitio ... Full text Cite

Special issue on experimental aspects of quantum computing

Journal article Quantum Information Processing · October 1, 2004 Full text Cite

Temperature dependence of energy transfer mechanisms in Eu-doped GaN

Journal article Journal of Applied Physics · June 15, 2004 Time-resolved photoluminescence measurements of the 5D 0→ 7F 2 and 5G 0→ 7F 3 transitions were performed for investigating the temperature-dependent energy transfer mec ... Full text Cite

Stimulated emission and time-resolved photoluminescence in rf-sputtered ZnO thin films

Journal article Applied Physics Letters · April 26, 2004 A measurement of stimulated emission (SE) from ZnO thin films grown on c-plane sapphire by rf sputtering was performed. At 10 K, free exciton transitions were observed in the photoluminescence (PL), transmission and reflection spectra of the sample anneale ... Full text Cite

Stimulated emission and ultrafast carrier relaxation in AlGaN/GaN multiple quantum wells

Journal article Applied Physics Letters · June 9, 2003 The stimulated emission and ultrafast carrier relaxation in AlGaN/GaN multiple quantum wells were analyzed. The room temperature, time-resolved, differential transmission measurements were used to map the carrier relaxation mechanism for above barrier ener ... Full text Cite

Ultrafast carrier relaxation in GaN, (formula presented) and an (formula presented) multiple quantum well

Journal article Physical Review B Condensed Matter and Materials Physics · April 11, 2003 Room-temperature, wavelength-nondegenerate ultrafast pump/probe measurements were performed on GaN and InGaN epilayers and an InGaN multiple quantum well (QW) structure. Carrier relaxation dynamics were investigated as a function of excitation wavelength a ... Full text Cite

Ultrafast carrier relaxation in GaN, In0.05Ga0.95N, and an In0.07Ga0.93N/In0.12Ga0.88N multiple quantum well

Journal article Physical Review B Condensed Matter and Materials Physics · April 1, 2003 Room-temperature, wavelength-nondegenerate ultrafast pump/probe measurements were performed on GaN and InGaN epilayers and an InGaN multiple quantum well (QW) structure. Carrier relaxation dynamics were investigated as a function of excitation wavelength a ... Cite

Stimulated emission and ultrafast carrier relaxation in InGaN multiple quantum wells

Journal article Applied Physics Letters · March 3, 2003 A study was performed on ultrafast carrier relaxation and simulated emission (SE) in InGaN multiple quantum wells (MQW). Two InGaN MQW laser structures with different QW In compositions x was used to measure SE. It was found that SE threshold energy densit ... Full text Cite

Enhanced radiative efficiency in GaN quantum dots grown by molecular beam epitaxy

Journal article IEEE Transactions on Nanotechnology · March 1, 2003 Self-assembled GaN quantum dots (QDs), grown on AlN by molecular beam epitaxy, were investigated by time-resolved photoluminescence spectroscopy. We investigate the emission mechanism in GaN QDs by comparing the carrier recombination dynamics in single and ... Full text Cite

Enhancement of spontaneous recombination rate in a quantum well by resonant surface plasmon coupling

Journal article Physical Review B Condensed Matter and Materials Physics · October 15, 2002 Using time-resolved photoluminescence measurements, the recombination rate in an In0.18Ga0.82N/GaN quantum well (QW) is shown to be greatly enhanced when spontaneous emission is resonantly coupled to a silver surface plasmon. The rate ... Full text Cite

Variable stars in the core of the globular cluster M3

Journal article Monthly Notices of the Royal Astronomical Society · September 21, 2002 We present the results of a survey for variable stars in the core of the globular cluster M3. Our findings include the discovery of 11 new or suspected variables, including a possible W Vir, and the first period determinations for 13 previously known varia ... Full text Cite

Enhancement of spontaneous emission rate by resonant surface plasmon coupling

Journal article Optics and Photonics News · January 1, 2002 Full text Cite

Systematic measurement of AlxGa1-xN refractive indices

Journal article Applied Physics Letters · December 17, 2001 Dispersion of the ordinary and extraordinary indices of refraction have been measured systematically for wurtzitic AlxGa1-xN epitaxial layers with 0.0≤x≤1.0 throughout the visible wavelength region. The dispersion, measured by a prism ... Full text Cite

Measurement of AlxGa1-xN Refractive Indices

Journal article Physica Status Solidi A Applied Research · November 1, 2001 Dispersion of the ordinary and extraordinary indices of refraction have been measured systematically for wurtzitic AlxGa1-xN epitaxial layers with 0 ≤ x ≤ 1.0 throughout the visible wavelength region 457 nm < λ < 800 nm. The dispersio ... Full text Cite

Control of coherent acoustic phonons in semiconductor quantum wells.

Journal article Physical review letters · June 2001 Using subpicosecond optical pump-probe techniques, coherent zone-folded longitudinal acoustic phonons (ZFLAPs) were investigated in an InGaN multiple quantum well structure. A two-pump differential transmission technique was used to generate and control co ... Full text Cite

Control of coherent acoustic phonons

Journal article Optics and Photonics News · January 1, 2001 Control behavior of coherent acoustic phonons was studied. Acoustic phonons in semiconductor multiple quantum wells (MQW) are expected to have very long coherence times. Semiconductor MQWs produce zone folding of the acoustic phonon branch, allowing direct ... Full text Cite

Ultrafast optical characterization of carrier capture times in InxGa1-xN multiple quantum wells

Journal article Applied Physics Letters · July 3, 2000 Subpicosecond wavelength-degenerate differential transmission optical spectroscopy was used to characterize the electron capture time in a 10-period InxGa1-xN multiple-quantum-well (MQW) structure. Photoluminescence and photoluminesce ... Full text Cite

Refractive indices and absorption coefficients of MgxZn1-xO alloys

Journal article Applied Physics Letters · February 21, 2000 Indices of refraction for MgxZn1-xO epitaxial films grown by pulsed-laser deposition on sapphire substrates with x up to 0.36 were determined in the range of wavelength 457-968 nm by analysis of optical transmission spectra and prism- ... Full text Cite

Two-dimensional photonic crystal fabry-perot resonators with lossy dielectrics

Journal article IEEE Transactions on Microwave Theory and Techniques · December 1, 1999 Square and triangular lattice two-dimensional (2-D) photonic crystals (PC's) composed of lossy dielectric rods in air were constructed with a microwave bandgap between 4-8 GHz. Fabry-Perot resonators of varying length were constructed from two of these PC' ... Full text Cite

Guest editorial

Journal article IEEE Transactions on Microwave Theory and Techniques · November 1999 Full text Cite

Guest editorial: Electromagnetic crystal structures, design, synthesis, and applications

Journal article Journal of Lightwave Technology · November 1999 Full text Cite

Ordinary and extraordinary refractive indices for AlxGa1-xN epitaxial layers

Journal article Applied Physics Letters · July 5, 1999 A large variation in the dispersion data for AlxGa1.0-xN epitaxial layers is presented. An experimental study is conducted which no(λ) and ne(λ) were measured to an accuracy of approximately ±0.01 for five Al Full text Cite

Rotational Energy Transfer in Small Polyatomic Molecules

Journal article · January 1, 1995 This chapter discusses rotational energy transfer (RET) in small polyatomic molecules. It focuses on incoherent state-to-state rates that result from collisions between like molecules and on the relationship of these rates to fundamental molecular paramete ... Full text Cite

The temperature dependence of fast vibrational energy transfer processes in methyl fluoride

Journal article Molecular Physics · August 10, 1993 The temperature dependencies of two fast vibrational energy transfer processes in methyl fluoride (CH3F) have been measured between 120K and 400 K by means of time-resolved millimetre/submillimetre-infrared double resonance spectroscopy. The fir ... Full text Cite

Development and applications of materials exhibiting photonic band gaps

Journal article Journal of the Optical Society of America B Optical Physics · January 1, 1993 Full text Cite

Collisions and rotational spectroscopy

Journal article Journal of Molecular Spectroscopy · January 1, 1992 Motivated by Oka's early work on molecular collisions and especially collision-induced rotational transitions, this paper addresses progress in these areas. Particular attention is paid to recent extensions to lower energy collisions of astrophysical signi ... Full text Cite

Frequency stability and reproducibility of optically pumped far-infrared lasers

Journal article Applied Physics Letters · December 1, 1990 Direct measurements of the gain profile of optically pumped far-infrared lasers show that large shifts in the laser frequency can be caused by the absorption from thermal molecules on the laser transition. The absorption shifting greatly exacerbates pump f ... Full text Cite

Rotational energy transfer in CH3F: The ΔJ=n, ΔK=0 processes

Journal article Journal of Chemical Physics · January 1, 1990 We report the measurement of the rates of ΔJ=n, ΔK=0(|n| ≤ 10) processes for CH3F-CH3F collisions at 300 K. The data are derived from a time-resolved millimeter/ submillimeter-infrared double resonance investigation of both the 1 ... Full text Cite

A time-resolved study of rotational energy transfer into A and E symmetry species of 13CH3F

Journal article Journal of Chemical Physics · January 1, 1989 Rotational energy transfer processes into the A and E symmetry species of the symmetric top molecule 13CH3F have been studied. In this time-resolved double resonance experiment a tunable millimeter/ submillimeter wave spectrometer was ... Full text Cite

Collisional energy transfer in optically pumped far-infrared lasers

Journal article IEEE Journal of Quantum Electronics · January 1, 1987 A numerical simulation of collisional energy transfer in optically pumped far-infrared (OPFIR) lasers is presented along with a discussion of each collisional process and how it affects laser operation. A simulation is required to adequately describe these ... Full text Cite

Dynamics and tunability of a small optically pumped cw far-infrared laser

Journal article Applied Physics Letters · December 1, 1986 We report the development of an ultrasmall, optically pumped cw far-infrared (FIR) laser that provides substantial tunability. This laser operates at pressures significantly higher than the maximum allowed by currently accepted theory. We also report the d ... Full text Cite