Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session R32: Plasmonics and Beyond II: Ultrafast DynamicsFocus
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Sponsoring Units: DCP Chair: Teri Odom, Northwestern University Room: 332 |
Thursday, March 17, 2016 8:00AM - 8:12AM |
R32.00001: Quantum theory for plasmon-assisted local field enhancement Ilya Grigorenko We applied quantum theory for nonlocal response and plasmon-assisted field enhancement near a small metallic nanoscale antenna in the limit of weak incoming fields. A simple asymmetric bio-inspired design of the nanoantenna for polarization-resolved measurement is proposed. The spatial field intensity distribution was calculated for different field frequencies and polarizations. We have shown that the proposed design the antenna allows us to resolve the polarization of incoming photons. [Preview Abstract] |
Thursday, March 17, 2016 8:12AM - 8:24AM |
R32.00002: Propagating and localized surface plasmons in Ag nanostructures Maciej Dabrowski, Yanan Dai, Hrvoje Petek Plasmonic excitations strongly depend on the size, geometry and dielectric environment of nanoscale metals. Here, we study an epitaxially grown Ag nanostructures on Si(001) and Si(111) surfaces by Low Energy Electron Microscopy/Photoemission Electron Microscopy (LEEM/PEEM). Using the combination of LEEM and broadly tunable femtosecond laser excited multiphoton PEEM we image how single crystalline metallic nanostructures form and how plasmon excitations depend on the particle structure and laser excitation parameters. For Ag pyramids with the dimensions of few hundreds nanometers, dipolar and quadrupolar localized surface plasmons are observed. For Ag wires with several micrometer lengths, both localized and propagating surface plasmons can be excited, depending on the polarization, particle orientation and energy of the excitation. Finally, in larger Ag islands, several micrometers in size, the interference patterns are created by plasmon waves excited at the island edges. In addition to plasmonic response, light diffraction patterns around the Ag nanostrutures are discussed. [Preview Abstract] |
Thursday, March 17, 2016 8:24AM - 8:36AM |
R32.00003: Plasmon-exciton coupling at Ag nanocluster decorated TiO$_{\mathrm{2}}$(110) surface studied by time-resolved two-photon photoemission spectroscopy Shijing Tan, Adam Argondizzo, Hrvoje Petek We study the spectroscopy and electron dynamics at Ag nanocluster decorated TiO$_{\mathrm{2}}$(110) surface upon photoexcitation of plasmonic modes by two-photon photoemission spectroscopy (2PP). Depositing Ag onto a reduced rutile TiO$_{\mathrm{2}}$(110) surface at room temperature forms pancake-like Ag particles with an average diameter of 4 nm and height of 1.5 nm. Measurements of the 2PP yield from Ag/TiO$_{\mathrm{2}}$ surface with tunable femtosecond laser excitation show enhancement at plasmonic resonances. Exciting with s-polarization ($\vec{{S}})$ the plasmonic resonance enhancement has a single peak at 3.1 eV, whereas with p-polarization ($\vec{{P}})$ there is an additional more intense resonance at 3.8 eV. We attribute the 3.1 and 3.8 eV peaks to the in-plane and the surface-normal plasmon modes respectively. Crystal azimuth orientation dependent excitation with ($\vec{{S}})$ shows an anisotropy in the 2PP spectra for the 3.1 eV in-plane plasmon mode when the laser electric field is aligned in the [001] vs. $[1\bar{{1}}0]$ directions. The existence of two plasmon modes and the in-plane plasmon anisotropy imply that the plasmon modes are perturbed by coherent coupling with excitons in the rutile TiO$_{\mathrm{2}}$ substrate. We speculate that plasmon-exciton resonant energy transfer could play an important role in the plasmonically enhanced photocatalysis at the Ag/TiO$_{\mathrm{2}}$ surface. [Preview Abstract] |
Thursday, March 17, 2016 8:36AM - 9:12AM |
R32.00004: Plasmonics at the Space-Time Limit Invited Speaker: Martin Aeschlimann The optical response of metallic nanostructures exhibits fascinating properties: local field interference effects that lead to strong variations of the near field distribution on a subwavelength scale, local field enhancement, and long lasting electronic coherences. Coherent control in general exploits the phase properties of light fields to manipulate coherent processes. Originally developed for molecular systems these concepts have recently been adapted also to nano-optical phenomena. Consequently, the combination of ultrafast laser spectroscopy, i.e. illumination with broadband coherent light sources, and near-field optics, opens a new realm for nonlinear optics on the nanoscale. To circumvent the experimental limitation of optical diffraction we use a photoemission electron microscope (PEEM) that has been proved to be a versatile tool for the investigation of near field properties of nanostructures with a spatial resolution of only a few nanometers and that allows for new spectroscopy techniques with ultrafast time resolution [1,2]. We introduce a new spectroscopic method that determines nonlinear quantum-mechanical response functions beyond the optical diffraction limit. While in established coherent two-dimensional (2D) spectroscopy a four-wave-mixing response is measured using three ingoing and one outgoing wave, in 2D nanoscopy we employ four ingoing and no outgoing waves. This allows studying a broad range of phenomena not accessible otherwise such as space-time resolved coupling, transport, and Anderson localized photon modes [3, 4]. [1] M. Aeschlimann et al, Nature \textbf{446}, 301 (2007) [2] M. Aeschlimann et al, PNAS \textbf{107} (12), 5329 (2010) [3] M. Aeschlimann et al, Science \textbf{333}, 1723-1726 (2011) [4] M. Aeschlimann et al, Nature Photonics \textbf{9}, 663, (2015) [Preview Abstract] |
Thursday, March 17, 2016 9:12AM - 9:24AM |
R32.00005: Imaging of Surface Plasmons by Ultrafast Multi-Photon Photoemission Electron Microscopy Yanan Dai, Maciej Dabrowki, Hrvoje Petek Silver nanostructures on silicon substrates are characterized by Low Energy Electron Microscopy (LEEM) and their plasmonic modes are imaged by ultrafast femtosecond laser pulse with Multi-Photon Photoemission Electron Microscopy (mP-PEEM). Simulations of Surface Plasmon Polariton (SPP) and Localized Surface Plasmon (LSP) mP-PEEM images are performed by 3D finite difference time domain (FDTD) method in order to characterize the plasmonic excitations. We imaged and simulated the interference patterns of multiple SPPs launched at the edges of microns scale single-crystal Ag islands with excitation wavelengths covering whole visible range. In addition, we studied the plasmonically enhanced excitation and plasmonic field distributions on single-crystal Ag wires of a few microns in length. Finally, we studied plasmon dynamics by recording plasmon field evolution on Ag structures from FDTD simulation. [Preview Abstract] |
Thursday, March 17, 2016 9:24AM - 9:36AM |
R32.00006: EELS study of plasmon excitations in LPNE aluminum nanowires Rodolfo Lopez Jr, Jay Sharping, Erik Menke We present our current experimental investigations of plasmonic resonances of aluminum nanowire arrays. Ordered nanowires with well-defined shape and size distributions are fabricated on silicon wafers and TEM apertures using lithographically patterned nanowire electrodeposition (LPNE). The structures, which have sizes down to 40 nm in the z direction, and planar sizes varying up to to 200nm, exhibit prominent and tunable plasmon resonances which are visible in EELS spectra. The electron energy loss spectra is correlated to the native oxide layer thickness as well as growth parameters of the nanowire array. [Preview Abstract] |
Thursday, March 17, 2016 9:36AM - 9:48AM |
R32.00007: Excited carrier dynamics and transport in plasmonic nanostructures Ravishankar Sundararaman, Prineha Narang, Adam Jermyn, Harry Atwater, William Goddard III Surface plasmon resonances provide a pathway to efficiently capture electromagnetic radiation in sub-wavelength structures for energy conversion and photodetection at the nano scale. The complete mechanism involves several microscopic steps spanning length scales from atomic dimensions to tens or hundreds of nanometers, posing challenges for experimental characterization and for first-principles predictions. To provide the basis for predicting and optimizing the complex interplay of materials and geometric effects in plasmon decay-induced excited carrier phenomena, we combined \emph{ab initio} electronic structure calculations, electromagnetic simulations and Boltzmann transport models. In Au, Ag, Cu and Al nanostructures, we find that initial carrier distributions as well as their subsequent transport, relaxation and thermalization are sensitive to electronic structure, exhibiting strong asymmetries between electrons and holes. We predict energy-dependent spatially-resolved carrier distributions collected in plasmonic nanostructures with strong field inhomogeneities, and explore the possibility of tailoring materials and geometry to collect the carrier distributions needed for such applications as photochemically driven CO$_2$ reduction and water splitting. [Preview Abstract] |
Thursday, March 17, 2016 9:48AM - 10:24AM |
R32.00008: Solar upconversion with plasmonic hot carriers Invited Speaker: Jennifer A. Dionne Upconversion of sub-bandgap photons is a promising approach to exceed the Shockley-Queisser limit in solar technologies. Placed behind a solar cell, upconverting materials convert lower-energy photons transmitted through the cell to higher-energy above-bandgap photons that can then be absorbed by the cell and contribute to photocurrent. Because the upconverter is electrically isolated from the active cell, it need not be current-matched to the cell, nor will it add mid-gap recombination pathways. Calculations have indicated that single-junction cell efficiencies can exceed 44{\%} upon addition of an upconverter -- a significant improvement over the maximum cell efficiency of 30{\%} without an upconverter. However, due to the low quantum efficiencies and narrow absorption bandwidths of existing upconverters, such significant cell improvements have yet to be observed experimentally.~ \newline \newline In this presentation, we will describe an entirely new solar upconverting scheme based on hot-carrier injection from a plasmonic absorber to an adjacent semiconductor. The plasmonic system both induces upconversion based on injection of hot-electrons and hot-holes and also enhances light-matter interactions. Low-energy photons incident on a plasmonic particle generate hot electrons and hot holes, which are injected into a semiconducting quantum well and subsequently radiatively recombine. Importantly, the bandgap of the quantum well can be higher than the energy of the incident photon, enabling emission of a higher-energy photon than that absorbed. First, we present analytic calculations showing that efficiencies as high as 25{\%} are possible, significantly higher than existing solid-state upconverters, which are only 2-5{\%} efficient. We also describe how further improvements in the efficiency are possible by employing materials and geometries that allow for more efficient carrier injection. Then, we describe experiments on InGaN/GaN quantum wells decorated with Au disks. On their own, the InGaN/GaN quantum wells do not upconvert. With the addition of the gold disks, strong upconversion is observed. We show how this new upconversion scheme offers spectral tunability across visible and near-infrared frequencies, does not require coherent illumination, is a linear process, and can be broadband.\\ \\Contributing authors include Guru Naik and Alex Welch, Stanford University [Preview Abstract] |
Thursday, March 17, 2016 10:24AM - 10:36AM |
R32.00009: Detecting antibody-antigen reaction using nano ripple gold LSPR based biosensor Iram Saleem, Dharshana Wijesundera, Buddhi Tilakaratne, William Widger, Wei-Kan Chu We introduce a simple and cost-effective scheme for bio-sensing using nano-ripple structures. One-dimension metallic nano-ripple structures formed by gas cluster ion beam irradiation have shown polarization~of~light as well as the localized surface plasmon resonance. These localized surface plasmon resonance (LSPR) based bio sensors not only are capable of label free real time analytical detection but also show high sensitivity. The nano surface morphology determines the changes in the plasmonic properties of\sout{ }nanostructures hence the plasmonic response is tunable. By immobilizing a stable and sterically accessible monolayer of antibody on the surface of these substrates and loading different concentrations of the specific antigen we identified the shift in the LSPR peaks triggered by the change of dielectric function in the neighborhood of the structures. These plasmonic nano-metallic structures can be utilized to observe the shift in the LSPR resonance frequency due to the cycle of adsorption, re-adsorption and reactions taking place on the surface that can potentially be mapped in to reaction mechanics. The bio-sensor has monolayer molecule-coating sensitivity and specific selectivity. [Preview Abstract] |
Thursday, March 17, 2016 10:36AM - 10:48AM |
R32.00010: Unique signature of bivalent analyte surface plasmon resonance model: A model governed by non-linear differential equations Purushottam Tiwari, Xuewen Wang, Yesim Darici, Jin He, Aykut Uren Surface plasmon resonance (SPR) is a biophysical technique for the quantitative analysis of bimolecular interactions. Correct identification of the binding model is crucial for the interpretation of SPR data. Bivalent SPR model is governed by non-linear differential equations, which, in general, have no analytical solutions. Therefore, an analytical based approach cannot be employed in order to identify this particular model. There exists a unique signature in the bivalent analyte model, existence of an `optimal analyte concentration', which can distinguish this model from other biphasic models. The unambiguous identification and related analysis of the bivalent analyte model is demonstrated by using theoretical simulations and experimentally measured SPR sensorgrams. [Preview Abstract] |
(Author Not Attending)
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R32.00011: \textbf{Selective plasmon enhancement of fluorescence towards point of care disease diagnostics} Bishwambhar Sengupta, Jingyi Zhu, Ramakrishna Podila, Apparao Rao Surface plasmon coupled emission (SPCE) is a novel analytical technique in which the isotropic emission of a fluorophore is combined with the surface plasmon resonance of a metal thin film to yield highly directional emission from the so-called plasmaphore and thus greatly increased sensitivity. The optimal SPCE enhancement is achieved by introducing a spacer layer to mitigate fluorescence-quenching arising from metal-fluorophore interactions. ~Here we report a \textgreater 10-fold amplification of rhodamine B (RhB) fluorophore when carbon nanomaterials are used as the spacer layer. By combining experimental and density functional theory studies, we found that the rehybridization between CNMs and RhB results in emission redshift. We present SPCE-based biosensors for smart-phone based sensing of different analytes including biomarkers for diseases such as tuberculosis. [Preview Abstract] |
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