| 1. |
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| 2. |
- Redjai Sani, Sohrab, et al.
(författare)
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Mutually synchronized bottom-up multi-nanocontact spin-torque oscillators
- 2013
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4, s. 2731-
-
Tidskriftsartikel (refereegranskat)abstract
- Spin-torque oscillators offer a unique combination of nanosize, ultrafast modulation rates and ultrawide band signal generation from 100 MHz to close to 100 GHz. However, their low output power and large phase noise still limit their applicability to fundamental studies of spin-transfer torque and magnetodynamic phenomena. A possible solution to both problems is the spin-wave-mediated mutual synchronization of multiple spin-torque oscillators through a shared excited ferromagnetic layer. To date, synchronization of high-frequency spin-torque oscillators has only been achieved for two nanocontacts. As fabrication using expensive top-down lithography processes is not readily available to many groups, attempts to synchronize a large number of nanocontacts have been all but abandoned. Here we present an alternative, simple and cost-effective bottom-up method to realize large ensembles of synchronized nanocontact spin-torque oscillators. We demonstrate mutual synchronization of three high-frequency nanocontact spin-torque oscillators and pairwise synchronization in devices with four and five nanocontacts.
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| 3. |
- Tong, Lianming, 1981, et al.
(författare)
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Highly directional bottom-up 3D nanoantenna for visible light
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Controlling light at the nanoscale is of fundamental importance and is essential for applications ranging from optical sensing and metrology to information processing, communications, and quantum optics. Considerable efforts are currently directed towards optical nanoantennas that directionally convert light into strongly localized energy and vice versa. Here we present highly directional 3D nanoantenna operating with visible light. We demonstrate a simple bottom-up approach to produce macroscopic arrays of such nanoantennas and present a way to address their functionality via interaction with quantum dots (QDs), properly embedded in the structure of the nanoantenna. The ease and accessibility of this structurally robust optical antenna device prompts its use as an affordable test bed for concepts in nano-optics and nanophotonics applications.
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| 4. |
- Armelles, G., et al.
(författare)
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Focus on magnetoplasmonics
- 2014
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- In this 'focus on' collection, a snapshot of the new, fast emerging field of magnetoplasmonics is presented. The research in the field deals with the combination of plasmonics and magnetism to elucidate the fundamentals of spinplasmon interactions and reach new functionalities such as the enhancement of magneto-optical activity in various materials, active control of plasmons with weak magnetic fields, magnetoplasmonics-based bio- and chemical sensing, magnetophotonic and magnetoplasmonic crystals as modulators of light transmission and reflection, and many others.
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| 5. |
- Bonanni, Valentina, et al.
(författare)
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Designer Magnetoplasmonics with Nickel Nanoferromagnets
- 2011
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 11:12, s. 5333-5338
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a new perspective on magnetoplasmonics in nickel nanoferromagnets by exploiting the phase tunability of the optical polarizability due to localized surface plasmons and simultaneous magneto-optical activity. We demonstrate how the concerted action of nanoplasmonics and magnetization can manipulate the sign of rotation of the reflected light's polarization (i.e., to produce Kerr rotation reversal) in ferromagnetic nanomaterials and, further, how this effect can be dynamically controlled and employed to devise conceptually new schemes for biochemosensing.
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| 6. |
- Cantono, Giada, et al.
(författare)
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Laser-driven proton acceleration from ultrathin foils with nanoholes
- 2021
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Structured solid targets are widely investigated to increase the energy absorption of high-power laser pulses so as to achieve efficient ion acceleration. Here we report the first experimental study of the maximum energy of proton beams accelerated from sub-micrometric foils perforated with holes of nanometric size. By showing the lack of energy enhancement in comparison to standard flat foils, our results suggest that the high contrast routinely achieved with a double plasma mirror does not prevent damaging of the nanostructures prior to the main interaction. Particle-in-cell simulations support that even a short scale length plasma, formed in the last hundreds of femtoseconds before the peak of an ultrashort laser pulse, fills the holes and hinders enhanced electron heating. Our findings reinforce the need for improved laser contrast, as well as for accurate control and diagnostics of on-target plasma formation.
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| 7. |
- Chen, Jianing, et al.
(författare)
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Plasmonic Nickel Nanoantennas
- 2011
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Ingår i: SMALL. - : Wiley. - 1613-6810 .- 1613-6829. ; 7:16, s. 2341-2347
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Tidskriftsartikel (refereegranskat)abstract
- The fundamental optical properties of pure nickel nanostructures are studied by far-field extinction spectroscopy and optical near-field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near-field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near-field and far-field spectra, dramatic shifts are found between the near-field and far-field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.
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| 8. |
- Chen, Si, 1985, et al.
(författare)
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Ultrahigh sensitivity made simple : nanoplasmonic label-free biosensing with an extremely low limit-of-detection for bacterial and cancer diagnostics.
- 2009
-
Ingår i: Nanotechnology. - : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 20:43
-
Tidskriftsartikel (refereegranskat)abstract
- We present a simple and robust scheme for biosensing with an ultralow limit-of-detection down to several pg cm(-2) (or several tens of attomoles cm(-2)) based on optical label-free biodetection with localized surface plasmon resonances. The scheme utilizes cost-effective optical components and comprises a white light source, a properly functionalized sensor surface enclosed in a simple fluidics chip, and a spectral analyzer. The sensor surface is produced by a bottom-up nanofabrication technique with hole mask colloidal lithography. Despite its simplicity, the method is able to reliably detect protein-protein binding events at low picomolar and femtomolar concentrations, which is exemplified by the label-free detection of the extracellular adherence protein (EAP) found on the outer surface of the bacterium Staphylococcus aureus and of prostate-specific antigen (PSA), which is believed to be a prostate cancer marker. These experiments pave the way towards an ultra-sensitive yet compact biodetection platform for point-of-care diagnostics applications.
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| 9. |
- Chen, W. H., et al.
(författare)
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Nanophotonics-based low-temperature PECVD epitaxial crystalline silicon solar cells
- 2016
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 49:12
-
Tidskriftsartikel (refereegranskat)abstract
- The enhancement of light absorption via nanopatterning in crystalline silicon solar cells is becoming extremely important with the decrease of wafer thickness for the further reduction of solar cell fabrication cost. In order to study the influence of nanopatterning on crystalline silicon thin-film solar cells, we applied two lithography techniques (laser interference lithography and nanoimprint lithography) combined with two etching techniques (dry and wet) to epitaxial crystalline silicon thin films deposited via plasma-enhanced chemical vapor deposition at 175 degrees C. The influence of nanopatterning with different etching profiles on solar cell performance is studied. We found that the etching profiles (pitch, depth and diameter) have a stronger impact on the passivation quality (open circuit voltage and fill factor) than on the optical performance (short circuit current density) of the solar cells. We also show that nanopatterns obtained via wet-etching can improve solar cell performance; and in contrast, dry-etching leads to poor passivation related to the etching profile, surface damage, and/ or contamination introduced during the etching process.
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| 10. |
- Depauw, V., et al.
(författare)
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Sunlight-thin nanophotonic monocrystalline silicon solar cells
- 2017
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Ingår i: Nano Futures. - : IOP Publishing. - 2399-1984. ; 1:2
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introducing nanophotonics into photovoltaics sets the path for scaling down the surface texture of crystalline-silicon solar cells from the micro-to the nanoscale, allowing to further boost the photon absorption while reducing silicon material loss. However, keeping excellent electrical performance has proven to be very challenging, as the absorber is damaged by the nanotexturing and the sensitivity to the surface recombination is dramatically increased. Here we realize a light-wavelength-scale nanotextured monocrystalline silicon cell with the confirmed efficiency of 8.6% and an effective thickness of only 830 nm. For this we adopt a self-assembled large-area and industry-compatible amorphous ordered nanopatterning, combined with an advanced surface passivation, earning strongly enhanced solar light absorption while retaining efficient electron collection. This prompts the development of highly efficient flexible and semitransparent photovoltaics, based on the industrially mature monocrystalline silicon technology.
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| 11. |
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| 12. |
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| 13. |
- Dmitriev, Alexander, 1975
(författare)
-
Future directions: Nanoplasmonic sensing tomorrow
- 2012
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Ingår i: Nanoplasmonic Sensors. - New York, NY : Springer New York. - 9781461439332 ; , s. 385-387
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Nanoplasmonic sensors have made an impressive progress from the conceptual idea to the working devices just in about one decade. It is apparent now that the promises of this technology-high sensitivity, compactness, readily available multiplexing capabilities-can be realized and implemented in a large number of areas, both in research settings and in prototype or even consumer devices. The research interest to the field is also strong-just recently a series of articles appeared that overviewed the current development of the research in nanoplasmonic sensors [1-4]. So, where do we go from here?
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| 14. |
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| 15. |
- Dmitriev, Alexander, 1975
(författare)
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Highly directional nanoantennas and plasmon-organic photovoltaics from bottom-up
- 2013
-
Ingår i: International Conference on Transparent Optical Networks. - 2162-7339. - 9781479906826
-
Konferensbidrag (refereegranskat)abstract
- I discuss the advances in bottom-up nanoplasmonics that rely on nanofabrication with hole-mask colloidal lithography (HCL). Two examples are highly directional nanoantennas in the visible, and enhanced plasmon-organic photovoltaics.
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| 16. |
- Dmitriev, Alexander, 1975
(författare)
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Magnetoplasmonics for Active Control of Light
- 2015
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Ingår i: 2015 17th International Conference on Transparent Optical Networks. - 2162-7339. - 9781467378802 ; , s. 1-
-
Konferensbidrag (refereegranskat)abstract
- Here I discuss the possibilities given by combining magnetism and plasmonics to gain control over polarization and phase of light with magnetoplasmonic nanoantennas. The combination of high near-field confinement by nanoplasmonic antennas and enhanced magneto-optical effects in these antennas allows creating adaptive metasurfaces in the visible spectral range.
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| 17. |
- Dmitriev, Alexander, 1975
(författare)
-
Preface
- 2012
-
Ingår i: Nanoplasmonic Sensors. - New York, NY : Springer New York. - 9781461439325 ; , s. V-VIII
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This book is a compendium of the finest research in nanoplasmonic sensing done around the world in the last decade. It describes basic theoretical considerations of nanoplasmons in the dielectric environment, gives examples of the multitude of applications of nanoplasmonics in biomedical and chemical sensing, and provides an overview of future trends in optical and non-optical nanoplasmonic sensing. Specifically, readers are guided through both the fundamentals and the latest research in the two major fields nanoplasmonic sensing is applied to - bio- and chemo-sensing - then given the state-of-the-art recipes used in nanoplasmonic sensing research.
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| 18. |
- Edman Jönsson, Gustav, 1983, et al.
(författare)
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Nanoplasmon-enabled macroscopic thermal management
- 2014
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4, s. 5111-
-
Tidskriftsartikel (refereegranskat)abstract
- In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial.
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| 19. |
- El Daif, O., et al.
(författare)
-
Front side plasmonic effect on thin silicon epitaxial solar cells
- 2012
-
Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248. ; 104, s. 58-63
-
Tidskriftsartikel (refereegranskat)abstract
- We study the effect of metal nanoparticles, showing localised plasmonic resonances, on the spectrally resolved efficiency of thin film crystalline silicon solar cells. We investigate model structures: silver (Ag) nanodiscs on the surface of epitaxial cells grown on highly doped silicon substrates, with a controlled micron-scale thickness. The cells have no back reflector in order to exclusively study the effect of the front surface on their optical properties. The nanodiscs were deposited through hole-mask colloidal lithography, which is a low-cost, bottom-up and extremely versatile technique. As opposed to many other works, we use as benchmarks both bare silicon cells and cells with a dielectric antireflection coating. We optically observe a resonance showing an absorption increase, found to be controllable by the discs parameters. We also see an increase in short-circuit current with respect to bare cells, but we see a decrease in efficiency with respect to cells with a dielectric antireflection coating, due to losses at short wavelengths. As the material properties are not notably affected by the particles deposition, we show that the main loss mechanisms are an important parasitic absorption in the nanoparticles and destructive interferences.
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| 20. |
- El Daif, O., et al.
(författare)
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Silver nanodiscs for light scattering in thin epitaxial silicon solar cells: Influence of the disc radius
- 2011
-
Ingår i: Materials Research Society Symposium Proceedings. - : Springer Science and Business Media LLC. - 0272-9172. - 9781627482110 ; 1391, s. 75-80
-
Konferensbidrag (refereegranskat)abstract
- The effect of silver nanoparticles showing localised plasmonic resonances on the efficiency of thin film silicon solar cells is studied. Silver (Ag) nanodiscs were deposited on the surface of silicon cells grown on highly doped silicon substrates, through hole-mask colloidal lithography, which is a low-cost and bottom-up technique. The cells have no back reflector in order to exclusively study the effect of the front surface on their properties. Cells with nanoparticles were compared with both bare silicon cells and cells with an antireflection coating. We optically observe a resonance showing an absorption increase controllable by the disc radius. We also see an increase in efficiency with respect to bare cells, but we see a decrease in efficiency with respect to cells with an antireflection coating due to losses at wavelengths below the plasmon resonance. As the material properties are not notably affected by the particles deposition, the loss mechanism is an important absorption in the nanoparticles. We confirm this by numerical simulations.
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| 21. |
- Esteban, Ruben, et al.
(författare)
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Direct Near-Field Optical Imaging of Higher Order Plasmonic Resonances
- 2008
-
Ingår i: Nano Lett.. ; 8, s. 3155-
-
Tidskriftsartikel (refereegranskat)abstract
- We map in real space and by purely optical means near-field optical information of localized surface plasmon polariton (LSPP) resonancesexcited in nanoscopic particles. We demonstrate that careful polarization control enables apertureless scanning near-field optical microscopy(aSNOM) to image dipolar and quadrupolar LSPPs of the bare sample with high fidelity in both amplitude and phase. This establishes aroutine method for in situ optical microscopy of plasmonic and other resonant structures under ambient conditions.
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| 22. |
- Fabris, Stefano, et al.
(författare)
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Oxygen Dissociation by Concerted Action of Di-Iron Centers in Metal
- 2011
-
Ingår i: Nano Letters. - 1530-6992 .- 1530-6984. ; 11, s. 5414-
-
Tidskriftsartikel (refereegranskat)abstract
- The high chemical reactivity of unsaturated metalsites is a key factor for the development of novel devices withapplications in sensor engineering and catalysis. It is also centralin the research for sustainable energy concepts, e.g., the efficientproduction and conversion of chemical fuels. Here, we study theprocess of oxygen dissociation by a surface-supported metal organic network that displays close structural and functionalanalogies with the cofactors of non-heme enzymes. We synthesizea two-dimensional array of chemically active di-iron sites ona Cu(001) surface wheremolecular oxygen readily dissociates atroom temperature. We provide an atomic-level structural and electronic characterization before and after reaction by combiningscanning tunneling microscopy, X-ray absorption spectroscopy, and density functional theory. The latter identifies a novelmechanism for O2 dissociation controlled by the cooperative catalytic action of two Fe2+ ions. The high structural flexibility of theorganic ligands, the mobility of the metal centers, and the hydrogen bonding formation are shown to be essential for the functionalityof these active centers allowing to mimick biologically relevant reactions in a confined environment.
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| 23. |
- Fadaly, Elham, et al.
(författare)
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Production of nano-holes patten on Si(111) by colloidal lithography for growth of InAs nanowires
- 2015
-
Ingår i: 15th International Conference on Nanotechnology.
-
Konferensbidrag (refereegranskat)abstract
- Colloidal lithography is a simple, versatile and low-cost technique that can be used to pattern diverse nanostructures on a wafer scale. In this work, colloidal lithography utilizing polystyrene nanoparticles as a lift-off mask was used to produce nanohole patterns on Si (111) substrates. The hole size, which is determined by the size of the polystyrene particles, can be well controlled by oxygen plasma shrinking. Using this technique, we were able to obtain nanohole pattern with feature size down to 50 nm, which is close to the limit that conventional lithographic techniques can reach, in a time-efficient and cost effective manner. InAs nanowires were successfully grown on the patterned substrates using molecular beam epitaxy.
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| 24. |
- Fredriksson, Hans, 1974, et al.
(författare)
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Hole-Mask Colloidal Lithography
- 2007
-
Ingår i: Advanced Materials. ; 19, s. 4297-4302
-
Tidskriftsartikel (refereegranskat)
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| 25. |
- Gambardella, P., et al.
(författare)
-
Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface
- 2009
-
Ingår i: Nature Materials. - 1476-4660 .- 1476-1122. ; 8:3, s. 189-193
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetic atoms at surfaces may provide the ultimate paradigm of a solid-state magnetic memory exhibiting either classical , or quantum , behaviour. Individual atoms, however, are difficult to arrange in regular patterns1,2,3,4, . Moreover, their magnetic properties are dominated by interaction with the substrate, which, as in the case of Kondo systems, often leads to a decrease or quench of their local magnetic moment , . Here we show that the supramolecular assembly of Fe and 1,4-benzenedicarboxylic acid molecules on a Cu surface results in ordered arrays of high-spin mononuclear Fe centres on a 1.5 nm square grid. Lateral coordination with the molecular ligands yields unsaturated yet stable coordination bonds, which allow for the chemical modification of the electronic and magnetic properties of the Fe atoms independently from the substrate. The easy magnetization direction of the Fe centres can be switched by oxygen adsorption, thus opening a way to control the magnetic anisotropy in supramolecular layers akin to that employed in metallic thin films , , , .
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| 26. |
- Hedsten, Karin, 1964, et al.
(författare)
-
Downscaling Optical Biosensing System
- 2008
-
Ingår i: Proceedings of Micro System Workshop 2008 (MSW08) 6-7 Maj, Göteborg, Sweden. ; MSW08, s. S2-6, s. 205-
-
Konferensbidrag (refereegranskat)
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| 27. |
- Hedsten, Karin, 1964, et al.
(författare)
-
Optical Label-Free Nanoplasmonic Biosensing Using a Vertical-Cavity Surface-Emitting Laser and Charge-Coupled Device
- 2010
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 82:4, s. 1535-1539
-
Tidskriftsartikel (refereegranskat)abstract
- We present a compact platform for biochemosensing based on the combination of a vertical-cavity surface- emitting laser (VCSEL) light source, microelectrome- chanical systems (MEMS)-based microoptics, a specially designed nanoplasmonic sensing chip, and charge- coupled device (CCD) detector. The platform does not require any spectral analyzer for signal evaluation, show- ing good promise for facile integration, neither does it use any microscope setup for the signal collection or imaging. The analytical capabilities of the developed biochemosens- ing platform are demonstrated by evaluation of the protein-substrate (biotinylated bovine serum albumin- gold) and the protein-protein (biotin-NeutrAvidin) bind- ing kinetics, which is further compared to detection based on conventional optical extinction spectroscopy. The instrument is able to detect low femtomoles of adsorbed proteins with the limit of detection comparable to the state-of-the-art research and commercial optical label-free biochemosensors.
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| 28. |
- Jain, S., et al.
(författare)
-
Broadband absorption enhancement in ultra-thin crystalline Si solar cells by incorporating metallic and dielectric nanostructures in the back reflector
- 2015
-
Ingår i: Progress in Photovoltaics: Research and Applications. - : Wiley. - 1099-159X .- 1062-7995. ; 23:9, s. 1144-1156
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a back reflecting scheme in order to enhance the maximum achievable current in one micron thick crystalline silicon solar cells. We perform 3D numerical investigations of the scattering properties of metallic nanostructures located at the back side and optimize them for enhancing absorption in the silicon layer. We validate our numerical results experimentally and also compare the absorption enhancement in the solar cell structure, both with quasi-periodic and random metallic nanostructures. We have looked at the interplay between the metallic nanostructures and an integrated back reflector. We show that the combination of metallic nanoparticles and a metallic reflector results in significant parasitic absorption. We compared this to another implementation based on titanium dioxide nanoparticles, which act as a Lambertian reflector of light. Our simulation and experimental results show that this proposed configuration results in reduced absorption losses and in broadband enhancement of absorption for ultra-thin solar cells, paving the way to an optimal back reflector for thin film photovoltaics.
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| 29. |
- Jain, S., et al.
(författare)
-
Broadband absorption enhancement in ultra-thin crystalline silicon solar cells by incorporating low cost aluminum nanoparticles
- 2013
-
Ingår i: 39th IEEE Photovoltaic Specialists Conference. ; , s. 555-559
-
Konferensbidrag (refereegranskat)abstract
- In this study nanodisks made from aluminum are incorporated in a back-reflector scheme in order to enhance the maximum achievable current in one-micron thick crystalline silicon solar cells. We perform three-dimensional numerical investigations of the backward scattering properties of aluminum nanodisks located at the back side, and optimize them for enhancing the absorption in the silicon layer. We also compare our results with previously optimized silver nanodisks and show that Al nanodisks are nearly as efficient as Ag counterpart. We show that if the absorption in the metallic back reflector (flat metal layer) can be avoided; this results in a further enhancement in absorption in the ultra-thin silicon layer. The proposed configuration results in a broadband (500nm to 1200nm) enhancement of absorption (∼ 58 %) for ultra-thin solar cells and has a great potential in thin film photovoltaic.
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| 30. |
- Khusin, Worawut, et al.
(författare)
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Long-Distance Indirect Excitation of Nanoplasmonic Resonances
- 2011
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:7, s. 2765-2769
-
Tidskriftsartikel (refereegranskat)abstract
- In nanoscopic systems, size, geometry, and arrangement are the crucial determinants of the light-matter interaction and resulting nanoparticles excitation. At optical frequencies, one of the most prominent examples is the excitation of localized surface plasmon polaritons, where the electromagnetic radiation is coupled to the confined charge density oscillations. Here, we show that beyond direct near- and far-field excitation, a long-range, indirect mode of particle excitation is available in nanoplasmonic systems. In particular, in amorphous arrays of plasmonic nanodiscs we find strong collective and coherent influence on each particle from its entire active neighborhood. This dependency of the local field response on excitation conditions at distant areas brings exciting possibilities to engineer enhanced electromagnetic fields through controlled, spatially configured illumination.
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| 31. |
- Kuttruff, Joel, et al.
(författare)
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Sub-picosecond collapse of molecular polaritons to pure molecular transition in plasmonic photoswitch-nanoantennas
- 2023
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723 .- 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular polaritons are hybrid light-matter states that emerge when a molecular transition strongly interacts with photons in a resonator. At optical frequencies, this interaction unlocks a way to explore and control new chemical phenomena at the nanoscale. Achieving such control at ultrafast timescales, however, is an outstanding challenge, as it requires a deep understanding of the dynamics of the collectively coupled molecular excitation and the light modes. Here, we investigate the dynamics of collective polariton states, realized by coupling molecular photoswitches to optically anisotropic plasmonic nanoantennas. Pump-probe experiments reveal an ultrafast collapse of polaritons to pure molecular transition triggered by femtosecond-pulse excitation at room temperature. Through a synergistic combination of experiments and quantum mechanical modelling, we show that the response of the system is governed by intramolecular dynamics, occurring one order of magnitude faster with respect to the uncoupled excited molecule relaxation to the ground state.
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| 32. |
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| 33. |
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| 34. |
- Lodewijks, Kristof, 1984, et al.
(författare)
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Multiscale conformal pattern transfer
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6, s. article no. 28490 -
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano-or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics.
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| 35. |
- Maccaferri, Nicolò, et al.
(författare)
-
Effects of a non-absorbing substrate on the magneto-optical Kerr response of plasmonic ferromagnetic nanodisks
- 2014
-
Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 211:5, s. 1067-1075
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetoplasmonics is an emerging field of intense research on materials combining magnetic and plasmonic functionalities. The novel optical and magneto-optical (MO) properties displayed by these materials could allow the design of a new class of magnetically controllable optical nano-devices. In this work, we investigate the effects of a non-absorbing (insulating) substrate on the MO activity of pure ferromagnetic disk-shaped nanostructures supporting localized plasmon resonances. We show that the red-shift of the localized plasmon resonance, related to the modification of the localization of the electromagnetic field due to the substrate, is not the only effect that the substrate has on the MO response. We demonstrate that the reflectivity of the substrate itself plays a key role in determining the MO response of the system. We discuss why it is so and provide a description of the modeling tools suitable to take into account both effects. Understanding the role of the substrate will permit a more aware design of magnetoplasmonic nanostructured devices for future biotechnological and optoelectronic applications. [GRAPHICS] Ferromagnetic nickel nanodisk in vacuum (left) and on a non-absorbing substrate (right), illuminated by linearly polarized light. The polarization of the reflected field is changed in the first case due to a combination of intrinsic magneto-optical properties and the nanoconfinement of the material. In the second case, the polarization of the reflected light is affected also by the presence of the substrate.
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| 36. |
- Maccaferri, N., et al.
(författare)
-
Polarizability and magnetoplasmonic properties of magnetic general nanoellipsoids
- 2013
-
Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:8, s. 9875-9889
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Tidskriftsartikel (refereegranskat)abstract
- An approach to compute the polarizability tensor of magnetic nanoparticles having general ellipsoidal shape is presented. We find a surprisingly excellent quantitative agreement between calculated and experimental magneto-optical spectra measured in the polar Kerr configuration from nickel nanodisks of large size (exceeding 100 nm) with circular and elliptical shape. In spite of its approximations and simplicity, the formalism presented here captures the essential physics of the interplay between magneto-optical activity and the plasmonic resonance of the individual particle. The results highlight the key role of the dynamic depolarization effects to account for the magneto-optical properties of plasmonic nanostructures.
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| 37. |
- McCarthy, Donald, et al.
(författare)
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Performance evaluation for aged environmentally adapted lubricants in bronze-steel sliding contacts
- 2008
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Ingår i: Journal of Synthetic Lubrication. - : Wiley. - 0265-6582 .- 1557-6841. ; 25, s. 115-
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Tidskriftsartikel (refereegranskat)abstract
- Environmentally adapted lubricants (EALs) are becoming of increasing interest to the industry as legislation demands the replacement of mineral oil lubricants. However, little or nothing is known about the infl uence of ageing on the performance of these fluids in mixed and boundary lubricated tribological contacts. In this study, samples of three fully formulated lubricating oils, both in their 'unaged' form and 'aged' by means of an oxidation process in the laboratory, were utilized in a detailed study whereby variations in relative lubrication performance were examined. Standard laboratory pin-on-disc equipment was utilized in order to allow comparisons to be made and the definition of conclusions for a sliding tin bronze on steel contact. This simulated the interaction between an oil-lubricated bronze bushing and steel shaft as found in the vane adjustment mechanism of a Kaplan turbine. X-ray photoelectron spectroscopy analysis was employed to assess the effect on surface layer structural chemistry. Results showed, for the specific application being investigated, that EALs continue to function well in terms of their friction and wear performance even at high acid numbers.
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| 38. |
- Mendoza-Galvan, A., et al.
(författare)
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Fano interference in supported gold nanosandwiches with weakly coupled nanodisks
- 2012
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 20:28, s. 29646-29658
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Tidskriftsartikel (refereegranskat)abstract
- We studied the far-field optical response of supported gold-silica-gold nanosandwiches using spectroscopic ellipsometry, reflectance and transmittance measurements. Although transmittance data clearly shows that the gold nanodisks in the sandwich structure interact very weakly, oblique reflectance spectra of s- and p-polarized light show clearly asymmetric line-shapes of the Fano type. However, all experimental results are very well described by modeling the gold nanodisks as oblate spheroids and by employing a 2 x 2 scattering matrix formulation of the Fresnel coefficients provided by an island film theory. In particular, the Fano asymmetry can be explained in terms of interference between the scattered waves from the decoupled nanodisks in the spectral range limited by their respective plasmon resonances. We also show that the reflectance and ellipsometry spectra can be described by a three-layer system with uniaxial effective dielectric functions.
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| 39. |
- Mendoza-Galvan, A., et al.
(författare)
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Optical response of supported gold nanodisks
- 2011
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Ingår i: Optics Express. - : Optical Society of America (OSA). - 1094-4087. ; 19:13, s. 12093-12107
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the ellipsometric spectra of short range ordered planar arrays of gold nanodisks supported on glass substrates can be described by modeling the nanostructured arrays as uniaxial homogeneous layers with dielectric functions of the Lorentz type. However, appreciable deviations from experimental data are observed in calculated spectra of irradiance measurements. A qualitative and quantitative description of all measured spectra is obtained with a uniaxial effective medium dielectric function in which the nanodisks are modeled as oblate spheroids. Dynamic depolarization factors in the long-wavelength approximation and interaction with the substrate are considered. Similar results are obtained calculating the optical spectra using the island-film theory. Nevertheless, a small in-plane anisotropy and quadrupolar coupling effects reveal a very complex optical response of the nanostructured arrays.
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| 40. |
-
Nanoplasmonic Sensors
- 2012
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- This book is a compendium of the finest research in nanoplasmonic sensing done around the world in the last decade. It describes basic theoretical considerations of nanoplasmons in the dielectric environment, gives examples of the multitude of applications of nanoplasmonics in biomedical and chemical sensing, and provides an overview of future trends in optical and non-optical nanoplasmonic sensing. Specifically, readers are guided through both the fundamentals and the latest research in the two major fields nanoplasmonic sensing is applied to – bio- and chemo-sensing – then given the state-of-the-art recipes used in nanoplasmonic sensing research.
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| 41. |
- Niesen, B., et al.
(författare)
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Plasmonic Efficiency Enhancement of High Performance Organic Solar Cells with a Nanostructured Rear Electrode
- 2013
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 3:2, s. 145-150
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Tidskriftsartikel (refereegranskat)abstract
- A strategy and implementation for efficiency enhancement of optimized high performance organic solar cells by a plasmonic nanostructured Ag rear electrode is presented. This enhancement is achieved by tuning the surface plasmon resonance of the nanostructures to the active layer absorption tail, which generates enhanced absorption by light scattering, as verified by experiment and simulation. © 2013 WILEY-VCH Verlag GmbH and Co.
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| 42. |
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| 43. |
- Pakizeh, Tavakol, 1977, et al.
(författare)
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Structural asymmetry and induced optical magnetism in plasmonic nanosandwiches
- 2008
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Ingår i: J. Opt. Soc. Am. B. ; 25, s. 659-
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Tidskriftsartikel (refereegranskat)abstract
- A number of recent studies have shown that hybridized antiphase dipolar plasmons, qualitatively similar tomagnetic dipole resonances, can be excited in metal–dielectric–metal structures over a wide frequency range.Here, we study how structural asymmetry in plasmonic nanosandwiches, composed of two Au disks separatedby a thin SiO2 layer, affects their near- and far-field optical properties using point-dipole analysis, electrodynamicssimulations, and optical spectroscopy. We find that the strength of the antiphase resonant mode can beincreased significantly compared to a symmetrical sandwich if the diameters or thicknesses of the nanodisks inthe sandwich are made to differ. Such asymmetrical nanosandwiches also exhibit a generally stronger magneticresponse, as characterized by the magnetic near-field enhancement in the region between the disks. However,symmetry breaking also leads to pronounced directionality effects in the magnetic near-field, i.e., the enhancementdepends on which side of the sandwich that is first illuminated.
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| 44. |
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| 45. |
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| 46. |
- Pirzadeh Irannezhad, Zhaleh, 1985, et al.
(författare)
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Plasmon-Interband Coupling in Nickel Nanoantennas
- 2014
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 1:3, s. 158-162
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Tidskriftsartikel (refereegranskat)abstract
- Plasmonic excitations are usually attributed to the free electron response at visible frequencies in the classic plasmonic metals Au and Ag. However, the vast majority of metals exhibit spectrally localized interband transitions or broad interband transition backgrounds in the energy range of interest for nanoplasmonics. Nevertheless, the interaction of interband transitions with localized plasmons in optical nanoantennas has hitherto received relatively little attention, probably because interband transitions are regarded as highly unwanted due to their strong damping effect on the localized plasmons. However, with an increasing number of metals (beyond Au and Ag) being considered for nanoplasmonic applications such as hydrogen sensing (Pd), UV-SERS (Al), or magnetoplasmonics (Ni, Fe, Co), a deeper conceptual understanding of the interactions between a localized plasmon mode and an interband transition is very important. Here, as a generic example, we examine the interaction of a localized (in energy space) interband transition with spectrally tunable localized plasmonic excitations and unearth the underlying physics in a phenomenological approach for the case of Ni disk nanoantennas. We find that plasmon interband interactions can be understood in the classical picture of two coupled harmonic oscillators, exhibiting the typical energy anticrossing fingerprint of a coupled system approaching the strong-coupling regime.
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| 47. |
- Rockstuhl, C., et al.
(författare)
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Large scale simulations in the realm of nanooptics
- 2010
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819480002 ; 7604
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The realm of nanooptics is usually characterized by the interaction of light with structures having relevant feature sizes much smaller than the wavelength. To model such problems, a large variety of methods exists. However, most of them either require a periodic arrangement of a unit cell or can handle only single entities. But there exists a great variety of functional devices which may have either a spatial extent much larger than the wavelength and which comprise structural details with sizes in the order of a fraction of the wavelength or they may consist of an amorphous arrangement of strongly scattering entities. Such structures require large scale simulations where the fine details are retained. In this contribution we outline our latest research on such devices and detail the computational peculiarities we have to overcome. Presenting several examples, we show how simulations support the physical understanding of these devices. Examples are randomly textured surfaces used for solar cells, where guided modes excited in the light absorbing layers strongly affect the solar cell efficiency, amorphous metamaterials and stochastically arranged nanoantennas. The usage of computational experiments will be motivated by the unprecedented insight into the functionality of such components. © 2010 Copyright SPIE - The International Society for Optical Engineering.
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| 48. |
- Rommel, Marcus, 1987, et al.
(författare)
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Sub-10 nm resolution after lift-off using HSQ./PMMA double layer resist
- 2013
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317. ; 110, s. 123-125
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen silesquioxan (HSQ) is a well-investigated negative tone inorganic resist [1,2] which is known for its capabilities for high resolution electron beam lithography (EBL) and its stability against dry etching [3]. In this paper, we introduce a process to create dense structures by EBL utilizing a layer of polymethyl-methacrylate (PMMA) as sacrificial layer beneath a HSQ layer. The sacrificial layer allows a simple lift-off process to remove the HSQ with organic solvents and thus avoids the use of hydrofluoric acid (HF) containing etchants, which is the commonly used HSQ remover [4]. The described double layer resist system allows patterning on substrates that are not HF compatible such as glass or oxide compounds, achieving a high resolution down to the sub-10 nm regime. Despite the use of a double layer resist, this process is applicable for arbitrarily large areas due to the remaining PMMA underneath the HSQ and the avoidance of undercuts.
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| 49. |
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| 50. |
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