1
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Bayles A, Fabiano CJ, Shi C, Yuan L, Yuan Y, Craft N, Jacobson CR, Dhindsa P, Ogundare A, Mendez Camacho Y, Chen B, Robatjazi H, Han Y, Strouse GF, Nordlander P, Everitt HO, Halas NJ. Tailoring the aluminum nanocrystal surface oxide for all-aluminum-based antenna-reactor plasmonic photocatalysts. Proc Natl Acad Sci U S A 2024; 121:e2321852121. [PMID: 38442156 PMCID: PMC10945844 DOI: 10.1073/pnas.2321852121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/24/2024] [Indexed: 03/07/2024] Open
Abstract
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 various gases and thermal conditions induces substantial, systematic changes in their surface oxide, modifying crystalline phase, surface morphology, density, and defect type and concentration. Tailoring the surface oxide properties enables AlNCs to function as all-aluminum-based antenna-reactor plasmonic photocatalysts, with the modified surface oxides providing varying reactivities and selectivities for several chemical reactions.
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Affiliation(s)
- Aaron Bayles
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | | | - Chuqiao Shi
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX77005
| | - Lin Yuan
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | - Yigao Yuan
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | - Nolan Craft
- Department of Physics & Astronomy, Rice University, Houston, TX77005
| | - Christian R. Jacobson
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | - Parmeet Dhindsa
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | - Adebola Ogundare
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
| | - Yelsin Mendez Camacho
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX77005
| | - Banghao Chen
- Department of Chemistry, Florida State University, Tallahassee, FL32306
| | | | - Yimo Han
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX77005
| | | | - Peter Nordlander
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
- Department of Physics & Astronomy, Rice University, Houston, TX77005
| | - Henry O. Everitt
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
- Department of Physics & Astronomy, Rice University, Houston, TX77005
- Department of Electrical and Computer Engineering, Rice University, Houston, TX77005
- Army Development Command Army Research Laboratory-South, Rice University, Houston, TX77005
| | - Naomi J. Halas
- Department of Chemistry, Rice University, Houston, TX77005
- Laboratory for Nanophotonics, Rice University, Houston, TX77005
- Department of Physics & Astronomy, Rice University, Houston, TX77005
- Department of Electrical and Computer Engineering, Rice University, Houston, TX77005
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2
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Lee SH, Iglesias B, Everitt HO, Liu J. Controlling product selectivity in hybrid gas/liquid reactors using gas conditions, voltage, and temperature. Nanoscale 2023. [PMID: 37158198 DOI: 10.1039/d3nr00561e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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 remain about how to optimize conditions to produce desired products. Using an alkaline electrolyte to suppress hydrogen formation and a gas diffusion electrode catalyst composed of copper nanoparticles on carbon nanospikes, we investigate how hydrocarbon product selectivity in the CO2 reduction reaction in hybrid reactors depends on three experimentally controllable parameters: (1) supply of dry or humidified CO2 gas, (2) applied potential, and (3) electrolyte temperature. Changing from dry to humidified CO2 dramatically alters product selectivity from C2 products ethanol and acetic acid to ethylene and C1 products formic acid and methane. Water vapor evidently influences product selectivity of reactions that occur on the gas-facing side of the catalyst by adding a source of protons that alters reaction pathways and intermediates.
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Affiliation(s)
- Seung-Hoon Lee
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
| | | | - Henry O Everitt
- U.S. Army DEVCOM Army Research Laboratory-South/Rice University, 6100 Main St., Houston, TX 77005, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA.
| | - Jie Liu
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
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3
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Lee SA, Kuhs CT, Searles EK, Everitt HO, Landes CF, Link S. d-Band Hole Dynamics in Gold Nanoparticles Measured with Time-Resolved Emission Upconversion Microscopy. Nano Lett 2023; 23:3501-3506. [PMID: 37023287 DOI: 10.1021/acs.nanolett.3c00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
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 plasmonic gold nanoparticles have been investigated, hot hole lifetimes have not been as thoroughly studied in plasmonic systems. Here, we demonstrate time-resolved emission upconversion microscopy and use it to resolve the lifetime and energy-dependent cooling of d-band holes formed in gold nanoparticles by plasmon excitation and by following plasmon decay into interband and then intraband electron-hole pairs.
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Affiliation(s)
- Stephen A Lee
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Christopher T Kuhs
- U.S. Army DEVCOM Army Research Laboratory-South, Houston, Texas 77005, United States
| | - Emily K Searles
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Henry O Everitt
- U.S. Army DEVCOM Army Research Laboratory-South, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Christy F Landes
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Stephan Link
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
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4
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Yao W, Verdugo F, Everitt HO, Christiansen RE, Johnson SG. Designing structures that maximize spatially averaged surface-enhanced Raman spectra. Opt Express 2023; 31:4964-4977. [PMID: 36785451 DOI: 10.1364/oe.472646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 10/02/2022] [Indexed: 06/18/2023]
Abstract
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 formulation for optimizing incoherent emission. This leads to radically different designs than optimizing SERS emission at a single known location, as we illustrate using several 2D design problems addressing effects of hot-spot density, angular selectivity, and nonlinear damage. We obtain optimized structures that perform about 4 × better than coating with optimized spheres or bowtie structures and about 20 × better when the nonlinear damage effects are included.
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5
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Chevalier P, Piccardo M, Amirzhan A, Capasso F, Everitt HO. Accurately Measuring Molecular Rotational Spectra in Excited Vibrational Modes. Appl Spectrosc 2022; 76:1494-1503. [PMID: 35775457 DOI: 10.1177/00037028221111174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
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 vibrational modes with the same accuracy. Recently, it was demonstrated that virtually any rotational transition in excited vibrational modes of most molecules may be made to lase when pumped by a continuously tunable quantum cascade laser (QCL). Here, we demonstrate how an infrared QCL may be used to enhance absorption strength or induce lasing of terahertz rotational transitions in highly excited vibrational modes in order to measure their frequencies more accurately. To illustrate the concepts, we used a tunable QCL to excite v3 R-branch transitions in N2O and either enhanced absorption or induced lasing on 20 v3 rotational transitions, whose frequencies between 299 and 772 GHz were then measured using either heterodyne or modulation spectroscopy. The spectra were fitted to obtain the rotational constants B3 and D3, which reproduce the measured spectra to within the experimental uncertainty of ± 5 kHz. We then show how this technique may be generalized by estimating the threshold power to make any rotational transition lase in any N2O vibrational mode.
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Affiliation(s)
- Paul Chevalier
- Harvard John A. Paulson School of Engineering and Applied Sciences, 1812Harvard University, Cambridge, MA, USA
| | - Marco Piccardo
- Harvard John A. Paulson School of Engineering and Applied Sciences, 1812Harvard University, Cambridge, MA, USA
- Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Milan, Italy
| | - Arman Amirzhan
- Harvard John A. Paulson School of Engineering and Applied Sciences, 1812Harvard University, Cambridge, MA, USA
| | - Federico Capasso
- Harvard John A. Paulson School of Engineering and Applied Sciences, 1812Harvard University, Cambridge, MA, USA
| | - Henry O Everitt
- 1024DEVCOM Army Research Laboratory, Houston, TX, USA
- Department of Physics, 3065Duke University, Durham, NC, USA
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6
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Abstract
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 energy decay mechanisms. Here we introduce the use of earth-abundant plasmonic aluminum nanoparticles as a promising renewable detoxifier of the sulfur mustard simulant 2-chloroethylethylsulfide through gas phase photodecomposition. Analysis of the decomposition products indicates that C-S bond breaking is facilitated under illumination, while C-Cl breaking and HCl elimination are favored under thermocatalytic (dark) conditions. This difference in reaction pathways illuminates the potential of plasmonic nanoparticles to tailor reaction selectivity toward less hazardous products in the detoxification of chemical warfare agents. Moreover, the photocatalytic activity of the Al nanoparticles can be regenerated almost completely after the reaction concludes through a simple surface treatment.
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Affiliation(s)
- Minghe Lou
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory of Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Aaron Bayles
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory of Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Henry O Everitt
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Laboratory of Nanophotonics, Rice University, Houston, Texas 77005, United States
- U.S. Army DEVCOM Army Research Laboratory, Houston, Texas 77005, United States
| | - Naomi J Halas
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Laboratory of Nanophotonics, Rice University, Houston, Texas 77005, United States
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7
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Bayles A, Tian S, Zhou J, Yuan L, Yuan Y, Jacobson CR, Farr C, Zhang M, Swearer DF, Solti D, Lou M, Everitt HO, Nordlander P, Halas NJ. Al@TiO 2 Core-Shell Nanoparticles for Plasmonic Photocatalysis. ACS Nano 2022; 16:5839-5850. [PMID: 35293740 DOI: 10.1021/acsnano.1c10995] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
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 photocatalysis are antenna-reactor nanoparticles and nanostructures, which combine the strong light-coupling of plasmonic nanostructures with reactors that enhance chemical specificity. Here, we introduce Al@TiO2 core-shell nanoparticles, combining earth-abundant Al nanocrystalline cores with TiO2 layers of tunable thickness. We show that these nanoparticles are active photocatalysts for the hot electron-mediated H2 dissociation reaction as well as for hot hole-mediated methanol dehydration. The wavelength dependence of the reaction rates suggests that the photocatalytic mechanism is plasmonic hot carrier generation with subsequent transfer of the hot carriers into the TiO2 layer. The Al@TiO2 antenna-reactor provides an earth-abundant solution for the future design of visible-light-driven plasmonic photocatalysts.
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Affiliation(s)
- Aaron Bayles
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Shu Tian
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Jingyi Zhou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Lin Yuan
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Yigao Yuan
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Christian R Jacobson
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Corbin Farr
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Ming Zhang
- Department of Physics & Astronomy, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Dayne F Swearer
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - David Solti
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Minghe Lou
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Henry O Everitt
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
- U.S. Army DEVCOM Army Research Laboratory - South, Houston, Texas 77005, United States
| | - Peter Nordlander
- Department of Physics & Astronomy, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Naomi J Halas
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Department of Physics & Astronomy, Rice University, Houston, Texas 77005, United States
- Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
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8
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Chevalier P, Amirzhan A, Wang F, Piccardo M, Johnson SG, Capasso F, Everitt HO. Widely tunable compact terahertz gas lasers. Science 2019; 366:856-860. [DOI: 10.1126/science.aay8683] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/21/2019] [Indexed: 01/23/2023]
Affiliation(s)
- Paul Chevalier
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Arman Amirzhan
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Fan Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Marco Piccardo
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Steven G. Johnson
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Federico Capasso
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Henry O. Everitt
- U.S. Army Combat Capabilities Development Command Aviation and Missile Center, Redstone Arsenal, AL 35898, USA
- Department of Physics, Duke University, Durham, NC 27708, USA
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9
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Lou M, Swearer DF, Gottheim S, Phillips DJ, Simmons JG, Halas NJ, Everitt HO. Quantitative analysis of gas phase molecular constituents using frequency-modulated rotational spectroscopy. Rev Sci Instrum 2019; 90:053110. [PMID: 31153269 DOI: 10.1063/1.5093912] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/29/2019] [Indexed: 06/09/2023]
Abstract
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 reconstruction of integrated line strengths from modulated spectra, the correlation of pressure-dependent line shape and strength with partial pressure, and the multiple standing wave interferences and modulation-induced line shape asymmetries that sensitively depend on source-chamber-detector alignment. Here, we introduce a quantitative analysis methodology that overcomes these challenges, reproducibly and accurately recovering gas molecule concentrations using a calibration procedure with a reference gas and a conversion based on calculated line strengths. The technique uses frequency-modulated rotational spectroscopy and recovers the integrated line strength from a Voigt line shape that spans the Doppler- and pressure-broadened regimes. Gas concentrations were accurately quantified to within the experimental error over more than three orders of magnitude, as confirmed by the cross calibration between CO and N2O and by the accurate recovery of the natural abundances of four N2O isotopologues. With this methodology, concentrations of hundreds of molecular species may be quantitatively measured down to the femtomolar regime using only a single calibration curve and the readily available libraries of calculated integrated line strengths, demonstrating the power of this technique for the quantitative gas-phase detection, identification, and quantification.
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Affiliation(s)
- Minghe Lou
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Dayne F Swearer
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Samuel Gottheim
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Dane J Phillips
- IERUS Technologies, 2904 Westcorp Blvd., Suite 210, Huntsville, Alabama 35805, USA
| | - Jay G Simmons
- U.S. Army Combat Capabilities Development Command, Aviation and Missile Center, Redstone Arsenal, Alabama 35898, USA
| | - Naomi J Halas
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
| | - Henry O Everitt
- U.S. Army Combat Capabilities Development Command, Aviation and Missile Center, Redstone Arsenal, Alabama 35898, USA
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10
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Abstract
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 multiple recycling steps, as in the energy-intensive Haber-Bosch process for ammonia synthesis. Here we report that illumination of a conventional ruthenium-based catalyst produces ammonia with high reaction rates and high conversion yields. Indeed, using continuous wave light-emitting diodes that simulate concentrated solar illumination, ammonia is copiously produced without any external heating or elevated pressures. The possibility of nonthermal plasmonic effects are excluded by carefully comparing the catalytic activity under direct and indirect illumination. Instead, thermal gradients, created and controlled by photothermal heating of the illuminated catalyst surface, are shown to be responsible for the high reaction rates and conversion yields. This nonisothermal environment enhances both by balancing the conflicting requirements of kinetics and thermodynamics, heralding the use of optically controlled thermal gradients as a universal, scalable strategy for the catalysis of many exothermic chemical reactions.
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Affiliation(s)
- Xueqian Li
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Xiao Zhang
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Henry O Everitt
- Army Aviation & Missile RD&E Center , Redstone Arsenal , Alabama 35898 , United States
- Department of Physics , Duke University , Durham , North Carolina 27708 , United States
| | - Jie Liu
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
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11
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Zhang X, Li X, Reish ME, Zhang D, Su NQ, Gutiérrez Y, Moreno F, Yang W, Everitt HO, Liu J. Plasmon-Enhanced Catalysis: Distinguishing Thermal and Nonthermal Effects. Nano Lett 2018; 18:1714-1723. [PMID: 29438619 DOI: 10.1021/acs.nanolett.7b04776] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
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 rate, the effects of photothermal heating and thermal gradients in the catalyst bed must be confidently and quantitatively characterized. This is a challenging task considering the conflating effects of light absorption, heat transport, and reaction energetics. Here, we introduce a methodology to distinguish the thermal and nonthermal contributions from plasmon-enhanced catalysts, demonstrated by illuminated rhodium nanoparticles on oxide supports to catalyze the CO2 methanation reaction. By simultaneously measuring the total reaction rate and the temperature gradient of the catalyst bed, the effective thermal reaction rate may be extracted. The residual nonthermal rate of the plasmon-enhanced reaction is found to grow with a superlinear dependence on illumination intensity, and its apparent quantum efficiency reaches ∼46% on a Rh/TiO2 catalyst at a surface temperature of 350 °C. Heat and light are shown to work synergistically in these reactions: the higher the temperature, the higher the overall nonthermal efficiency in plasmon-enhanced catalysis.
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Affiliation(s)
- Xiao Zhang
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Xueqian Li
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Matthew E Reish
- Army Aviation & Missile RD&E Center , Redstone Arsenal , Alabama 35898 , United States
| | - Du Zhang
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Neil Qiang Su
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Yael Gutiérrez
- Optics Group, Department of Applied Physics , University of Cantabria , Avda de Los Castros , s/n 39005 Santander , Spain
| | - Fernando Moreno
- Optics Group, Department of Applied Physics , University of Cantabria , Avda de Los Castros , s/n 39005 Santander , Spain
| | - Weitao Yang
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
- Department of Physics , Duke University , Durham , North Carolina 27708 , United States
| | - Henry O Everitt
- Army Aviation & Missile RD&E Center , Redstone Arsenal , Alabama 35898 , United States
- Department of Physics , Duke University , Durham , North Carolina 27708 , United States
| | - Jie Liu
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
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12
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Gutiérrez Y, Ortiz D, Saiz JM, González F, Everitt HO, Moreno F. The UV Plasmonic Behavior of Distorted Rhodium Nanocubes. Nanomaterials (Basel) 2017; 7:E425. [PMID: 29207569 PMCID: PMC5746915 DOI: 10.3390/nano7120425] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 01/25/2023]
Abstract
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 concentrations are located at the corners and edges of the nanocubes, exactly where they are the most spectroscopically and catalytically active. Because intense catalytic activity at corners and edges will reshape these nanoparticles, distortions of the cubical shape, including surface concavity, surface convexity, and rounded corners and edges, are also explored to quantify how significantly these distortions deteriorate their plasmonic and photocatalytic properties. The fact that the highest fields and highest carrier concentrations occur in the corners and edges of Rh nanocubes (NCs) confirms their tremendous potential for plasmon-enhanced spectroscopy and catalysis. It is shown that this opportunity is fortuitously enhanced by the fact that even higher field and charge concentrations reside at the interface between the metal nanoparticle and a dielectric or semiconductor support, precisely where the most chemically active sites are located.
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Affiliation(s)
- Yael Gutiérrez
- Department of Applied Physics, University of Cantabria, Avda. Los Castros, s/n., 39005 Santander, Spain.
| | - Dolores Ortiz
- Department of Applied Physics, University of Cantabria, Avda. Los Castros, s/n., 39005 Santander, Spain.
| | - José M Saiz
- Department of Applied Physics, University of Cantabria, Avda. Los Castros, s/n., 39005 Santander, Spain.
| | - Francisco González
- Department of Applied Physics, University of Cantabria, Avda. Los Castros, s/n., 39005 Santander, Spain.
| | - Henry O Everitt
- Department of Physics, Duke University, Durham, NC 27708, USA.
- U.S. Army Aviation and Missile RD&E Center, Redstone Arsenal, Huntsville, AL 35898, USA.
| | - Fernando Moreno
- U.S. Army Aviation and Missile RD&E Center, Redstone Arsenal, Huntsville, AL 35898, USA.
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13
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Richard JT, Heimbeck MS, Blake Autin L, Everitt HO. Wide bandwidth, millimeter-resolution inverse synthetic aperture radar imaging. J Opt Soc Am A Opt Image Sci Vis 2017; 34:1073-1079. [PMID: 29036115 DOI: 10.1364/josaa.34.001073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 05/12/2017] [Indexed: 06/07/2023]
Abstract
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-scale accuracy using super-resolution techniques. Radon transform reconstructions of the returns from rotated targets approached the image quality of the complete data set in a fraction of the time by sampling as few as 10 angles. The limitations of shooting-and-bouncing ray simulations at high frequencies are illustrated through a critical comparison of their predictions with the measured data and the method of moments simulations, indicating the importance of accurately capturing the obfuscating role played by multipath interference in complex targets.
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14
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Zhang X, Li X, Zhang D, Su NQ, Yang W, Everitt HO, Liu J. Product selectivity in plasmonic photocatalysis for carbon dioxide hydrogenation. Nat Commun 2017; 8:14542. [PMID: 28230100 PMCID: PMC5348736 DOI: 10.1038/ncomms14542] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/11/2017] [Indexed: 12/19/2022] Open
Abstract
Photocatalysis has not found widespread industrial adoption, in spite of decades of active research, because the challenges associated with catalyst illumination and turnover outweigh the touted advantages of replacing heat with light. A demonstration that light can control product selectivity in complex chemical reactions could prove to be transformative. Here, we show how the recently demonstrated plasmonic behaviour of rhodium nanoparticles profoundly improves their already excellent catalytic properties by simultaneously reducing the activation energy and selectively producing a desired but kinetically unfavourable product for the important carbon dioxide hydrogenation reaction. Methane is almost exclusively produced when rhodium nanoparticles are mildly illuminated as hot electrons are injected into the anti-bonding orbital of a critical intermediate, while carbon monoxide and methane are equally produced without illumination. The reduced activation energy and super-linear dependence on light intensity cause the unheated photocatalytic methane production rate to exceed the thermocatalytic rate at 350 °C.
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Affiliation(s)
- Xiao Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Xueqian Li
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Du Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Neil Qiang Su
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Weitao Yang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Henry O. Everitt
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
- Army Aviation & Missile RD&E Center, Redstone Arsenal, Alabama 35898, USA
| | - Jie Liu
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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15
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Gutierrez Y, Ortiz D, Sanz JM, Saiz JM, Gonzalez F, Everitt HO, Moreno F. How an oxide shell affects the ultraviolet plasmonic behavior of Ga, Mg, and Al nanostructures. Opt Express 2016; 24:20621-31. [PMID: 27607666 DOI: 10.1364/oe.24.020621] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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 native oxide shell surrounds nanostructures of these metals that affects their plasmonic response. Here, through a nanoparticle-oxide core-shell model, we present a detailed electromagnetic analysis of how oxidation alters the UV-plasmonic response of spherical or hemisphere-on-substrate nanostructures made of those metals by analyzing the spectral evolution of two parameters: the absorption efficiency (far-field analysis) and the enhancement of the local intensity averaged over the nanoparticle surface (near-field analysis).
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16
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Akyildiz HI, Stano KL, Roberts AT, Everitt HO, Jur JS. Photoluminescence Mechanism and Photocatalytic Activity of Organic-Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration. Langmuir 2016; 32:4289-4296. [PMID: 27063955 DOI: 10.1021/acs.langmuir.6b00285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
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) spectroscopy approach. The optical activity of the modified fibers depends on infiltration thermal processing conditions and is attributed to the reaction mechanisms taking place at different temperatures. At low temperatures a single excitation band and dual emission bands are observed, while, at high temperatures, two distinct absorption bands and one emission band are observed, suggesting that the physical and chemical structure of the resulting hybrid material depends on the SVI temperature. Along with enhancing the photoluminescence intensity of the PET fibers, the internal quantum efficiency also increased to 5-fold from ∼4-5% to ∼24%. SVI processing also improved the photocatalytic activity of the fibers, as demonstrated by photodeposition of Ag and Au metal particles out of an aqueous metal salt solution onto fiber surfaces via UVA light exposure. Toward applications in flexible electronics, well-defined patterning of the metallic materials is achieved by using light masking and focused laser rastering approaches.
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Affiliation(s)
- Halil I Akyildiz
- Department of Textile Engineering, Chemistry and Science, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Kelly L Stano
- Department of Textile Engineering, Chemistry and Science, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Adam T Roberts
- Army Aviation and Missile Research, Development, and Engineering Center , Redstone Arsenal, Alabama 35898, United States
| | - Henry O Everitt
- Army Aviation and Missile Research, Development, and Engineering Center , Redstone Arsenal, Alabama 35898, United States
- Department of Physics, Duke University , Durham, North Carolina 27708, United States
| | - Jesse S Jur
- Department of Textile Engineering, Chemistry and Science, North Carolina State University , Raleigh, North Carolina 27695, United States
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17
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Alabastri A, Yang X, Manjavacas A, Everitt HO, Nordlander P. Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles. ACS Nano 2016; 10:4835-4846. [PMID: 27045994 DOI: 10.1021/acsnano.6b01851] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
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 remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures.
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Affiliation(s)
| | | | - Alejandro Manjavacas
- Department of Physics and Astronomy, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Henry O Everitt
- Army Aviation and Missile RD&E Center at Redstone Arsenal , Huntsville, Alabama 35898, United States
- Department of Physics, Duke University , Durham, North Carolina 27708, United States
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18
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Zhou L, Zhang C, McClain MJ, Manjavacas A, Krauter CM, Tian S, Berg F, Everitt HO, Carter EA, Nordlander P, Halas NJ. Aluminum Nanocrystals as a Plasmonic Photocatalyst for Hydrogen Dissociation. Nano Lett 2016; 16:1478-84. [PMID: 26799677 DOI: 10.1021/acs.nanolett.5b05149] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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 achieve high efficiency under mild conditions. Here we demonstrate that aluminum nanocrystals (Al NCs), when illuminated, can be used as a photocatalyst for hydrogen dissociation at room temperature and atmospheric pressure, despite the high activation barrier toward hydrogen adsorption and dissociation. We show that hot electron transfer from Al NCs to the antibonding orbitals of hydrogen molecules facilitates their dissociation. Hot electrons generated from surface plasmon decay and from direct photoexcitation of the interband transitions of Al both contribute to this process. Our results pave the way for the use of aluminum, an earth-abundant, nonprecious metal, for photocatalysis.
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Affiliation(s)
| | | | | | - Alejandro Manjavacas
- Department of Physics and Astronomy, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | | | | | - Felix Berg
- Johannes Gutenberg University Mainz , D 55099 Mainz, Germany
| | - Henry O Everitt
- Army Aviation and Missile RD&E Center, Redstone Arsenal , Alabama 35898, United States
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19
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Zhang X, Li P, Barreda Á, Gutiérrez Y, González F, Moreno F, Everitt HO, Liu J. Size-tunable rhodium nanostructures for wavelength-tunable ultraviolet plasmonics. Nanoscale Horiz 2016; 1:75-80. [PMID: 32260606 DOI: 10.1039/c5nh00062a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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 polyol methods to synthesize monodisperse Rh nanocubes with unprecedentedly large sizes and slightly concave faces. The associated local surface plasmon resonances (LSPRs) red-shifted with increasing sizes in the UV region from deep UV to around 400 nm, consistent with numerical simulations. UV illumination of p-aminothiophenol attached to the Rh nanocubes generated surface-enhanced Raman spectra and accelerated photo-decomposition, and these enhancements were largest for nanocubes whose LSPR was resonant with the UV laser. The lack of a native oxide coating, the precise control of nanocube size and morphology demonstrated here, and the ability to tune the surface plasmon resonance from the deep UV to near UV spectral region, make rhodium a compelling choice for UV plasmonic applications.
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Affiliation(s)
- Xiao Zhang
- Department of Chemistry, Duke University, Durham, NC 27708, USA.
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20
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King NS, Liu L, Yang X, Cerjan B, Everitt HO, Nordlander P, Halas NJ. Fano Resonant Aluminum Nanoclusters for Plasmonic Colorimetric Sensing. ACS Nano 2015; 9:10628-10636. [PMID: 26426492 DOI: 10.1021/acsnano.5b04864] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
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 of the spectrum. These nanoclusters can be designed with specific chromaticities in the blue-green region of the spectrum and exhibit a remarkable spectral sensitivity to changes in the local dielectric environment. We show that such structures can be used quite generally for colorimetric localized surface plasmon resonance (LSPR) sensing, where the presence of analytes is detected by directly observable color changes rather than through photodetectors and spectral analyzers. To quantify our results and provide a metric for optimization of such structures for colorimetric LSPR sensing, we introduce a figure of merit based on the color perception ability of the human eye.
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Affiliation(s)
| | | | | | | | - Henry O Everitt
- Army Aviation and Missile RD&E Center , Redstone Arsenal, Alabama 35898 United States
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21
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McClain MJ, Schlather AE, Ringe E, King NS, Liu L, Manjavacas A, Knight MW, Kumar I, Whitmire KH, Everitt HO, Nordlander P, Halas NJ. Aluminum nanocrystals. Nano Lett 2015; 15:2751-5. [PMID: 25790095 DOI: 10.1021/acs.nanolett.5b00614] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We demonstrate the facile synthesis of high purity aluminum nanocrystals over a range of controlled sizes from 70 to 220 nm diameter with size control achieved through a simple modification of solvent ratios in the reaction solution. The monodisperse, icosahedral, and trigonal bipyramidal nanocrystals are air-stable for weeks, due to the formation of a 2-4 nm thick passivating oxide layer on their surfaces. We show that the nanocrystals support size-dependent ultraviolet and visible plasmon modes, providing a far more sustainable alternative to gold and silver nanoparticles currently in widespread use.
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22
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Knight MW, Coenen T, Yang Y, Brenny BJM, Losurdo M, Brown AS, Everitt HO, Polman A. Gallium plasmonics: deep subwavelength spectroscopic imaging of single and interacting gallium nanoparticles. ACS Nano 2015; 9:2049-2060. [PMID: 25629392 DOI: 10.1021/nn5072254] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
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 fabricated by molecular-beam epitaxy make optical measurements of individual particles challenging. Here we employ hyperspectral cathodoluminescence (CL) microscopy to characterize the response of single Ga NPs of various sizes within an irregular ensemble by spatially and spectrally resolving both in-plane and out-of-plane plasmonic modes. These modes, which include hybridized dipolar and higher-order terms due to phase retardation and substrate interactions, are correlated with finite difference time domain (FDTD) electrodynamics calculations that consider the Ga NP contact angle, substrate, and native Ga/Si surface oxidation. This study experimentally confirms previous theoretical predictions of plasmonic size-tunability in single Ga NPs and demonstrates that the plasmonic modes of interacting Ga nanoparticles can hybridize to produce strong hot spots in the ultraviolet. The controlled, robust UV plasmonic resonances of gallium nanoparticles are applicable to energy- and phase-specific applications such as optical memory, environmental remediation, and simultaneous fluorescence and surface-enhanced Raman spectroscopies.
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Affiliation(s)
- Mark W Knight
- Center for Nanophotonics, FOM Institute AMOLF , Science Park Amsterdam 104, 1098 XG Amsterdam, The Netherlands
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23
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Watson AM, Zhang X, Alcaraz de la Osa R, Marcos Sanz J, González F, Moreno F, Finkelstein G, Liu J, Everitt HO. Rhodium nanoparticles for ultraviolet plasmonics. Nano Lett 2015; 15:1095-100. [PMID: 25602159 DOI: 10.1021/nl5040623] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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 p-aminothiophenol, local field-enhanced Raman spectra and accelerated photodamage were observed under near-resonant ultraviolet illumination, while charge transfer simultaneously increased fluorescence for up to 13 min. The combined local field enhancement and charge transfer demonstrate essential steps toward plasmonically enhanced ultraviolet photocatalysis.
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Affiliation(s)
- Anne M Watson
- Department of Physics and ‡Department of Chemistry, Duke University , Durham, North Carolina 27708, United States
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24
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Mrozack A, Heimbeck M, Marks DL, Richard J, Everitt HO, Brady DJ. Adaptive millimeter-wave synthetic aperture imaging for compressive sampling of sparse scenes. Opt Express 2014; 22:13515-13530. [PMID: 24921545 DOI: 10.1364/oe.22.013515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
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, inverse synthetic aperture RADAR reconstruction techniques are used to search for one or two wire scatterers within a specified range, while an adaptive algorithm determined successive sampling locations. The two-dimensional location of each scatterer is thereby identified with sub-wavelength accuracy in as few as 1/4 the number of lateral steps required for a simple raster scan. The implications of applying this approach to more complex scattering geometries are explored in light of the various assumptions made.
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25
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Roberts AT, Binder R, Kwong NH, Golla D, Cormode D, LeRoy BJ, Everitt HO, Sandhu A. Optical characterization of electron-phonon interactions at the saddle point in graphene. Phys Rev Lett 2014; 112:187401. [PMID: 24856720 DOI: 10.1103/physrevlett.112.187401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Indexed: 06/03/2023]
Abstract
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-acoustic phonon coupling in band structure renormalization. Using a Born approximation for electron-phonon coupling and experimental estimates of the dynamic lattice temperature, we compute the differential transmission line shape. Comparing the numerical and experimental line shapes, we deduce the effective acoustic deformation potential to be Deff(ac)≃5 eV. This value is in accord with recent theoretical predictions but differs from those extracted using electrical transport measurements.
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Affiliation(s)
- Adam T Roberts
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA and U.S. Army Aviation and Missile Research, Development, and Engineering Center, Redstone Arsenal, Alabama 35898, USA
| | - Rolf Binder
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA and Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Nai H Kwong
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
| | - Dheeraj Golla
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Daniel Cormode
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Brian J LeRoy
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Henry O Everitt
- U.S. Army Aviation and Missile Research, Development, and Engineering Center, Redstone Arsenal, Alabama 35898, USA
| | - Arvinder Sandhu
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA and Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
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26
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Abstract
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 amenability to manufacturing processes, makes aluminum a highly promising material for commercial applications. Fabricating Al-based nanostructures whose optical properties correspond with theoretical predictions, however, can be a challenge. In this work, the Al plasmon resonance is observed to be remarkably sensitive to the presence of oxide within the metal. For Al nanodisks, we observe that the energy of the plasmon resonance is determined by, and serves as an optical reporter of, the percentage of oxide present within the Al. This understanding paves the way toward the use of aluminum as a low-cost plasmonic material with properties and potential applications similar to those of the coinage metals.
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Affiliation(s)
- Mark W Knight
- Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, §Department of Chemistry, and ⊥Laboratory for Nanophotonics, Rice University , Houston, Texas 77005, United States
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27
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Yang Y, Callahan JM, Kim TH, Brown AS, Everitt HO. Ultraviolet nanoplasmonics: a demonstration of surface-enhanced Raman spectroscopy, fluorescence, and photodegradation using gallium nanoparticles. Nano Lett 2013; 13:2837-2841. [PMID: 23659187 DOI: 10.1021/nl401145j] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
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 permitted the demonstration of surface-enhanced Raman spectra, fluorescence, and degradation following excitation by a HeCd laser operating at 325 nm. Measured local Raman enhancement factors exceeding 10(7) demonstrate the potential of gallium nanoparticle arrays for plasmonically enhanced ultraviolet detection and remediation.
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Affiliation(s)
- Yang Yang
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
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28
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Knight MW, Liu L, Wang Y, Brown L, Mukherjee S, King NS, Everitt HO, Nordlander P, Halas NJ. Aluminum plasmonic nanoantennas. Nano Lett 2012; 12:6000-4. [PMID: 23072330 DOI: 10.1021/nl303517v] [Citation(s) in RCA: 226] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
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-producible plasmonic materials. Here we examine the properties of individual Al nanorod antennas with cathodoluminescence (CL). This approach allows us to image the local density of optical states (LDOS) of Al nanorod antennas with a spatial resolution less than 20 nm and to identify the radiative modes of these nanostructures across the visible and into the UV spectral range. The results, which agree well with finite difference time domain (FDTD) simulations, lay the groundwork for precise Al plasmonic nanostructure design for a variety of applications.
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Affiliation(s)
- Mark W Knight
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA
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29
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Heimbeck MS, Marks DL, Brady D, Everitt HO. Terahertz interferometric synthetic aperture tomography for confocal imaging systems. Opt Lett 2012; 37:1316-1318. [PMID: 22513671 DOI: 10.1364/ol.37.001316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
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 interferometric synthetic aperture microscopy are adapted to account for the diffraction-and defocusing-induced spatially varying THz beam width characteristic of narrow depth of focus, high-resolution confocal imaging. A frequency-swept two-dimensional TISAT confocal imaging instrument rapidly achieves in-focus, diffraction-limited resolution over a depth 12 times larger than the instrument's depth of focus in a manner that may be easily extended to three dimensions and greater depths.
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Affiliation(s)
- M S Heimbeck
- Charles M. Bowden Research Center, Army Aviation & Missile RD&E Center, Redstone Arsenal, Alabama 35898, USA.
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30
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Mattiucci N, D'Aguanno G, Everitt HO, Foreman JV, Callahan JM, Buncick MC, Bloemer MJ. Ultraviolet surface-enhanced Raman scattering at the plasmonic band edge of a metallic grating. Opt Express 2012; 20:1868-77. [PMID: 22274532 DOI: 10.1364/oe.20.001868] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
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. It is shown that these enhancements are directly linked to the spectral position of the plasmonic band edge of the metal/substrate surface plasmon. A simple methodology is presented for selecting the grating pitch to produce optimal enhancement for a given laser frequency.
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Affiliation(s)
- Nadia Mattiucci
- AEgis Tech., Nanogenesis Division, Huntsville, Alabama 35806, USA
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31
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Albella P, Garcia-Cueto B, González F, Moreno F, Wu PC, Kim TH, Brown A, Yang Y, Everitt HO, Videen G. Shape matters: plasmonic nanoparticle shape enhances interaction with dielectric substrate. Nano Lett 2011; 11:3531-7. [PMID: 21848270 DOI: 10.1021/nl201783v] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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 depends on nanostructure size, shape, and substrate. Large, polarization-dependent splittings arise from the broken symmetry of hemispherical gallium nanoparticles on sapphire substrates, inducing strong interactions with the substrate that depend sensitively on the angle of illumination and the nanoparticle diameter.
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Affiliation(s)
- Pablo Albella
- Grupo de Óptica, Departamento Física Aplicada, Universidad de Cantabria, 39005 Santander, Spain
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32
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Heimbeck MS, Kim MK, Gregory DA, Everitt HO. Terahertz digital holography using angular spectrum and dual wavelength reconstruction methods. Opt Express 2011; 19:9192-9200. [PMID: 21643173 DOI: 10.1364/oe.19.009192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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 reconstruction of amplitude and phase objects is performed digitally using the angular spectrum method in conjunction with Fourier space filtering to reduce noise from the twin image and DC term. Phase unwrapping is achieved using the dual wavelength method, which offers an automated approach to overcome the 2π phase ambiguity. Potential applications for nondestructive test and evaluation of visually opaque dielectric and composite objects are discussed.
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Affiliation(s)
- Martin S Heimbeck
- Army Aviation and Missile RD&E Center, Weapon Sciences Directorate, Redstone Arsenal, Alabama 35898, USA.
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33
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Chua SL, Caccamise CA, Phillips DJ, Joannopoulos JD, Soljacić M, Everitt HO, Bravo-Abad J. Spatio-temporal theory of lasing action in optically-pumped rotationally excited molecular gases. Opt Express 2011; 19:7513-7529. [PMID: 21503059 DOI: 10.1364/oe.19.007513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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 molecular collisional and diffusion processes characterizing the operation of this class of lasers. The effect on the main lasing features of the spatial variation of the electric field intensity and the ohmic losses associated to each cavity mode are also included in our analysis. Our simulations show that, for the exemplary case of methyl fluoride gas confined in a cylindrical copper cavity, the region of maximum population inversion is located near the cavity walls. Based on this fact, our calculations show that the lowest lasing threshold intensity corresponds to the cavity mode that, while maximizing the spatial overlap between the corresponding population inversion and electric-field intensity distributions, simultaneously minimizes the absorption losses occurring at the cavity walls. The dependence of the lasing threshold intensity on both the gas pressure and the cavity radius is also analyzed and compared with experiment. We find that as the cavity size is varied, the interplay between the overall gain of the system and the corresponding ohmic losses allows for the existence of an optimal cavity radius which minimizes the intensity threshold for a large range of gas pressures. The theoretical analysis presented in this work expands the current understanding of lasing action in optically-pumped far-infrared lasers and, thus, could contribute to the development of a new class of compact far-infrared and terahertz sources able to operate efficiently at room temperature.
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Affiliation(s)
- Song-Liang Chua
- Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139, USA.
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Ruffin PB, Brantley CL, Edwards E, Roberts JK, Chew W, Warren LC, Ashley PR, Everitt HO, Webster E, Foreman JV, Sanghadasa M, Crutcher SH, Temmen MG, Varadan V, Hayduke D, Wu PC, Khoury CG, Yang Y, Kim TH, Vo-Dinh T, Brown AS, Callahan J. Nanotechnology research and development for military and industrial applications. ACTA ACUST UNITED AC 2011. [DOI: 10.1117/12.878970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Heimbeck MS, Reardon PJ, Callahan J, Everitt HO. Transmissive quasi-optical Ronchi phase grating for terahertz frequencies. Opt Lett 2010; 35:3658-3660. [PMID: 21042382 DOI: 10.1364/ol.35.003658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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 diffractive orders and the diffraction efficiency were measured as a function of THz frequency and rotation angle. The grating performance depends sensitively on the refractive index, whose value can be measured with an accuracy limited by the fabrication precision. The use of these gratings for polarization-insensitive quasi-optical imaging and phased arrays is discussed.
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Affiliation(s)
- Martin S Heimbeck
- Army Aviation and Missile RD&E Center, Weapon Sciences Directorate, Redstone Arsenal, Alabama 35898, USA.
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Wu PC, Khoury CG, Kim TH, Yang Y, Losurdo M, Bianco GV, Vo-Dinh T, Brown AS, Everitt HO. Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles. J Am Chem Soc 2009; 131:12032-3. [PMID: 19655747 DOI: 10.1021/ja903321z] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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 nonsolution applications. Ga nanoparticles were grown using a simple molecular beam epitaxy-based fabrication protocol, and monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry allowed the nanoparticles to be easily controlled for size. The Raman spectra obtained from cresyl fast violet (CFV) deposited on substrates with differing mean nanoparticle sizes represent the first demonstration of enhanced Raman signals from reproducibly tunable self-assembled Ga nanoparticles. Nonoptimized aggregate enhancement factors of approximately 80 were observed from the substrate with the smallest Ga nanoparticles for CFV dye solutions down to a dilution of 10 ppm.
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Affiliation(s)
- Pae C Wu
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
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Wu PC, Losurdo M, Kim TH, Giangregorio M, Bruno G, Everitt HO, Brown AS. Plasmonic gallium nanoparticles on polar semiconductors: interplay between nanoparticle wetting, localized surface plasmon dynamics, and interface charge. Langmuir 2009; 25:924-30. [PMID: 19105600 DOI: 10.1021/la802678y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
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 wetting of Ga nanoparticles and on the resulting surface plasmon resonance (SPR) by exploiting real time plasmonic ellipsometry. The interface potential between polar semiconductors (SiC, GaN, and ZnO) and plasmonic nanoparticles (gallium) is shown to influence nanoparticle formation dynamics, geometry, and consequently the SPR wavelength. We invoke the Lippman electrowetting framework to elucidate the mechanisms controlling nanoparticle dynamics and experimentally demonstrate that the charge transfer at the Ga nanoparticle/polar semiconductor interface is an intrinsic method for tailoring the nanoparticle plasmon resonance. Therefore, the present data demonstrate that for supported nanoparticles, surface and interface piezoelectric charge of polar semiconductors also affects SPR along with the well-known effect of the media refractive index.
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Affiliation(s)
- Pae C Wu
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
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Affiliation(s)
- Jianye Li
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Physical Chemistry, University of Science & Technology Beijing, Beijing, China
| | - Hongying Peng
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
- Present address: GE Global Research Center, Niskayuna, New York 12309, USA
| | - Jie Liu
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Henry O. Everitt
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
- U.S. Army Aviation & Missile Research, Development & Engineering Center, Redstone Arsenal, Alabama 35898, USA
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Foreman JV, Li J, Peng H, Choi S, Everitt HO, Liu J. Time-resolved investigation of bright visible wavelength luminescence from sulfur-doped ZnO nanowires and micropowders. Nano Lett 2006; 6:1126-30. [PMID: 16771566 DOI: 10.1021/nl060204z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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 edge ultraviolet emission, and a spectral distribution that closely matches the dark-adapted human eye response. By comparatively studying sulfur-doped and undoped ZnO micropowders, we clarify how sulfur doping and nanostructuring affect the visible luminescence and the underlying energy transfer mechanisms.
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Affiliation(s)
- John V Foreman
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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Abstract
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 coherent ZFLAP oscillations through the relative timing and amplitude of the two pump pulses. Enhancement and suppression of ZFLAP oscillations were demonstrated, including complete cancellation of generated acoustic phonons for the first time in any material system. Coherent control was used to demonstrate that ZFLAPs are generated differently in InGaN multiple quantum wells than in GaAs/AlAs superlattices.
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Affiliation(s)
- U Ozgür
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
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