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https://www.readbyqxmd.com/read/27910853/holographic-free-electron-light-source
#1
Guanhai Li, Brendan P Clarke, Jin-Kyu So, Kevin F MacDonald, Nikolay I Zheludev
Recent advances in the physics and technology of light generation via free-electron proximity and impact interactions with nanostructures (gratings, photonic crystals, nano-undulators, metamaterials and antenna arrays) have enabled the development of nanoscale-resolution techniques for such applications as mapping plasmons, studying nanoparticle structural transformations and characterizing luminescent materials (including time-resolved measurements). Here, we introduce a universal approach allowing generation of light with prescribed wavelength, direction, divergence and topological charge via point-excitation of holographic plasmonic metasurfaces...
December 2, 2016: Nature Communications
https://www.readbyqxmd.com/read/27910072/enhancing-surface-plasmon-resonance-detection-using-nanostructured-au-chips
#2
Ivan Indutnyi, Yuriy Ushenin, Dirk Hegemann, Marianne Vandenbossche, Victor Myn'ko, Mariia Lukaniuk, Petro Shepeliavyi, Andrii Korchovyi, Roman Khrystosenko
The increase of the sensitivity of surface plasmon resonance (SPR) refractometers was studied experimentally by forming a periodic relief in the form of a grating with submicron period on the surface of the Au-coated chip. Periodic reliefs of different depths and spatial frequency were formed on the Au film surface using interference lithography and vacuum chalcogenide photoresists. Spatial frequencies of the grating were selected close to the conditions of Bragg reflection of plasmons for the working wavelength of the SPR refractometer and the used environment (solution of glycerol in water)...
December 2016: Nanoscale Research Letters
https://www.readbyqxmd.com/read/27908751/enhanced-potency-of-bivalent-small-molecule-gp41-inhibitors
#3
Vladimir Sofiyev, Hardeep Kaur, Beth A Snyder, Priscilla A Hogan, Roger G Ptak, Peter Hwang, Miriam Gochin
Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer...
November 19, 2016: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/27908641/free-energy-perturbation-calculation-of-relative-binding-free-energy-between-broadly-neutralizing-antibodies-and-the-gp120-glycoprotein-of-hiv-1
#4
Anthony J Clark, Tatyana Gindin, Baoshan Zhang, Lingle Wang, Robert Abel, Colleen S Murret, Fang Xu, Amy Bao, Nina J Lu, Tongqing Zhou, Peter D Kwong, Lawrence Shapiro, Barry Honig, Richard A Friesner
Direct calculation of relative binding affinities between antibodies and antigens is a long-sought goal. However, despite substantial efforts, no generally applicable computational method has been described. Here we describe a systematic free energy perturbation (FEP) protocol and calculate the binding affinities between the gp120 envelope glycoprotein of HIV-1 and three broadly neutralizing antibodies (bNAbs) of the VRC01 class. The protocol has been adapted from successful studies of small molecules to address the challenges associated with modeling protein-protein interactions...
November 28, 2016: Journal of Molecular Biology
https://www.readbyqxmd.com/read/27906396/gadolinium-oxysulfide-coated-gold-nanorods-with-improved-stability-and-dual-modal-magnetic-resonance-photoacoustic-imaging-contrast-enhancement-for-cancer-theranostics
#5
Tao Guo, Yan Lin, Zhi Li, Shan Chen, Guoming Huang, Huirong Lin, Jun Wang, Gang Liu, Huang-Hao Yang
Gold nanorods (GNRs) are emerging as a promising nanoplatform for cancer theranostics because of their unique optical properties. However, they still suffer from many limitations, such as high cytotoxicity, low thermodynamic and biological stability, and a tedious process for integrating other imaging modalities, for further practical biomedical applications. In this work, a strategy by one-step coating of Gd2O2S around GNRs is reported to address these limitations of GNRs. After the coating of the Gd2O2S shell, the as-fabricated Gd2O2S coated GNRs (GNRs@Gd2O2S) show enhanced biocompatibility and photostability, and tunable localized surface plasmon resonance...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906395/regioselective-plasmonic-nano-assemblies-for-bimodal-sub-femtomolar-dopamine-detection
#6
Fengli Gao, Liqiang Liu, Gang Cui, Liguang Xu, Xiaoling Wu, Hua Kuang, Chuanlai Xu
Reliable and ultrasensitive quantification of dopamine (DA) is essential in the precise diagnotherapy of neurological diseases. In this study, dual mode counterpropagating-responsive gold@silver nanoparticle-gold nanorod (Au@AgNP-AuNR) nano-assemblies were fabricated for the precise quantification of DA. The plasmonic Au@AgNP-AuNR assemblies possessed high surface-enhanced Raman scattering (SERS) activity and strong fluorescence quenching, due to the prominent electromagnetic enhancement between the hotspots of the assemblies...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906371/depolarization-of-a-randomly-distributed-plasmonic-meander-metasurface-characterized-by-mueller-matrix-spectroscopic-ellipsometry
#7
Liwei Fu, Audrey Berrier, Huiyu Li, Philipp Schau, Karsten Frenner, Martin Dressel, Wolfgang Osten
Metallic nanostructures offer efficient solutions in polarization control with a very low thickness. In this report, we investigate the optical properties of a nano-fabricated plasmonic pseudo-depolarizer using Mueller matrix spectroscopic ellipsometry in transmission configuration. The depolarizer is composed of 256 square cells, each containing a periodically corrugated metallic film with random orientation. The full Mueller matrix was analyzed as a function of incident angle in a range between 0 and 20° and over the whole rotation angle range...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906356/enhanced-infrared-transmission-through-gold-nanoslit-arrays-via-surface-plasmons-in-continuous-graphene
#8
Zizhuo Liu, Koray Aydin
Graphene is a monolayer plasmonic material that has been widely studied in the area of plasmonics and nanophotonics. Combining graphene with traditional plasmonic structures provides new opportunities and challenges. One particular application for nanostructured metals is enhanced optical transmission. However, extraordinary transmission (EOT) is known to have a frequency-selective performance due to size and periodicity of the nanohole arrays. Here, we propose to use a continuous graphene layer to enhance transmission through gold nanoslit arrays at mid-infrared (mid-IR) wavelengths...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906355/control-of-the-two-photon-fluorescence-of-quantum-dots-coupled-to-silver-nanowires
#9
Weijie Mai, Xiaokang Song, Ping Jiang, Wenzhong Wang, Li Yu, Jiasen Zhang
Plasmon-based fluorescence modulation has led to important advances in various fields and has paved the way toward promising scientific research aimed at enabling new applications. However, the modulation of fluorescence properties based on both localized surface plasmon (LSP) and cavity modes of propagating surface plasmon polaritons (SPPs) are rarely reported. Here, we raster scanned a hybrid nanowire (HNW) with quantum dots (QDs) adsorbed onto a Ag nanowire (NW) and obtained two-photon fluorescence (TPF) maps of the intensity and decay rate...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906345/grating-coupling-based-excitation-of-bloch-surface-waves-for-lab-on-fiber-optrodes
#10
Michele Scaravilli, Giuseppe Castaldi, Andrea Cusano, Vincenzo Galdi
In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906327/optical-force-enhancement-and-annular-trapping-by-plasmonic-toroidal-resonance-in-a-double-disk-metastructure
#11
Ren-Chao Jin, Jie Li, Ying-Hua Wang, Ming-Jie Zhu, Jia-Qi Li, Zheng-Gao Dong
Optical forces can be enhanced by surface plasmon resonances with various interesting characteristics. Here, we numerically calculated the optical forces enhanced by a new kind of toroidal dipolar resonance in a double-disk metastructure. The results show that this kind of optical force is competitive with ordinary plasmonic forces and typically can reach-182.5pNμm<sup>2</sup>mW<sup>-1</sup>. Influences of geometric parameters are discussed for the enhancement characteristic of optical force...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906326/improving-the-luminescence-enhancement-of-hybrid-au-nanoparticle-monolayer-mos-sub-2-sub-by-focusing-radially-polarized-beams
#12
Di Liu, Le Yu, Xiao Xiong, Lei Yang, Yan Li, Ming Li, Hai-Ou Li, Gang Cao, Ming Xiao, Bin Xiang, Chang-Jun Min, Guang-Can Guo, Xi-Feng Ren, Guo-Ping Guo
Monolayer transition-metal dichalcogenides (TMDs) have grown as fantastic building blocks for optoelectronic applications, owing to their direct band gap, transparency, and mechanical flexibility. Since the luminescence of monolayer TMDs suffers from low light absorption and emission, surface plasmons, which confine light at subwavelength and enhance the local electric field, are utilized to boost both excitation and emission fields of TMDs, enabling strong light-matter interaction at the nano-scale. Meanwhile, radially-polarized beams (RPBs) as new and attractive excitation source have found many applications in surface plasmon polaritons, optical tweezer and so on...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906315/effect-of-non-conformal-gold-deposition-on-sers-related-plasmonic-effects
#13
Swe Zin Oo, Martin D B Charlton
Recently, a comprehensive three dimensional computational model based on rigorous coupled wave analysis (RCWA) has been developed to investigate the properties of surface plasmons resident on metal coated arrays of inverted pyramidal pits used for SERS sensing applications in the form of 'klarite'. This simulation tool allows the identification of a variety of dispersive features including propagating and localized surface plasmons as well as simple diffraction relating to the influence of geometrical features...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906303/higher-order-surface-plasmon-contributions-to-passive-and-active-plasmonic-interferometry
#14
Dongfang Li, Jing Feng, Domenico Pacifici
We compare the intensity modulation of passive light transmission and active fluorescence emission in planar plasmonic interferometers consisting of a nano-scale hole flanked by circular grooves etched in a silver film. Discrete fast Fourier transform applied to plasmonic interferograms - i.e., optical interferograms obtained by varying the propagation phase of surface plasmon polaritons (SPPs) - reveals higher-order interference effects that can be enhanced by optimizing in-plane SPP scattering and reflection...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906222/effective-optical-constants-of-anisotropic-silver-nanoparticle-films-with-plasmonic-properties
#15
M N M N Perera, D Schmidt, W E K Gibbs, S Juodkazis, P R Stoddart
Mueller matrix ellipsometry has been used to determine the effective optical constants of island-like Ag films deposited by thermal evaporation. These films depart substantially from bulk silver with a prominent localized surface plasmon resonance. Moreover, despite the isotropic appearance, they exhibit uniaxial optical properties with the optical axis inclined by 83.4° from the substrate normal toward the direction of the incoming vapor flux. The uniaxial model supports the plasmon resonance peaks revealed by in-plane absorbance measurements of the films...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27906209/magnetization-induced-effects-in-second-harmonic-generation-under-the-lattice-plasmon-resonance-excitation
#16
I A Kolmychek, A N Shaimanov, A V Baryshev, T V Murzina
We present an experimental study of optical second harmonic generation (SHG) from arrays of nanostructures exhibiting collective plasmon resonances in the visible spectral range. Gold nanoparticles with the lateral diameter of 100 nm are packed in a square lattice with the period of 400 nm and are covered by a 90 nm thick iron garnet layer. We show an enhancement of SHG in the spectral vicinity of the lattice surface plasmon resonance. It is demonstrated that application of the external DC magnetic field results in a spectral shift of the SHG maximum up to 5 nm, accompanied by a pronounced phase modulation of the second harmonic wave...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27906202/experimental-demonstration-of-compact-spoof-localized-surface-plasmons
#17
Di Bao, Khalid Z Rajab, Wei Xiang Jiang, Qiang Cheng, Zhen Liao, Tie Jun Cui
In recent years, the study of generating and detecting localized surface plasmons (LSPs) has been expanded from the optical regime to microwave regime. In this Letter, the compact spoof LSPs are introduced through both numerical simulations and near-field measurements. It is observed that the compact LSP structure could effectively reduce the resonant frequency with a stronger resonance strength (G<sub>dBsm</sub>) and a higher Q-factor. Both electric near-field and surface-current distributions are monitored to examine the resonance processes of the LSP particle...
December 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27905323/plasmonic-nano-protrusions-hierarchical-nanostructures-for-single-molecule-raman-spectroscopy
#18
Sagnik Basuray, Avinash Pathak, Sangho Bok, Biyan Chen, Steven C Hamm, Cherian J Mathai, Suchismita Guha, Keshab Gangopadhyay, Shubhra Gangopadhyay
Classical methods for enhancing the electromagnetic field from substrates for spectroscopic applications, such as surface-enhanced Raman spectroscopy (SERS), have involved the generation of hotspots through directed self-assembly of nanoparticles or by patterning nanoscale features using expensive nanolithography techniques. A novel large-area, cost-effective soft lithographic technique involving glancing angle deposition (GLAD) of silver on polymer gratings is reported here. This method produces hierarchical nanostructures with high enhancement factors capable of analyzing single-molecule SERS...
December 1, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27904898/a-dual-photoluminescence-enhancement-system-stabilization-of-a-water-soluble-aiee-fluorogen-using-silver-nanowire
#19
Ying-Chen Chiang, Chun-Ta Huang, Wei Hsin Wang, Cheng-Chung Chang
This manuscript describes the preparation of water soluble aggregation-induced emission enhancement (AIEE)-based fluorescent organic nanoparticles (FONs). The fluorescence diversity of the FONs was investigated in the presence of silver nanowires. We observed that the emission of the FONs can be enhanced by mixing with the nanowires, which is believed to originate from resonance between the emission of the FONs and the surface plasmon resonances of the metal surface. That is, the AIEE phenomenon was promoted according to the metal-enhanced fluorescence (MEF) mechanism that can be used to build up a novel double emission enhancement (DEE) platform and to extend the range of AIEE applications...
December 1, 2016: Faraday Discussions
https://www.readbyqxmd.com/read/27898124/direction-resolved-radiation-from-polarization-controlled-surface-plasmon-modes-on-silver-nanowire-antennas
#20
Zhili Jia, Hong Wei, Deng Pan, Hongxing Xu
Metallic nanowires (NWs) support multiple surface plasmon (SP) modes, which lead to extraordinary SP propagation behaviors. The leaky SP modes in metallic NWs connect the guiding and radiation of light at the nanometer scale. Understanding and controlling these modes are of vital importance for various nanophotonic applications. Here, we investigate the radiation from two polarization-controlled SP modes on supported silver NWs by using leakage radiation imaging and Fourier imaging techniques. The radiation directions from these modes can be clearly resolved from the Fourier images...
November 29, 2016: Nanoscale
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