Plasmonic nanoparticles

Metal Clusters The Missing Link Between Single Atoms and Plasmonic Nanoparticles... 

The materials described in this chapter are denoted in the literature mostly as metal clusters or metal nanoclusters . However, the terminology metal clusters spans various scientific disciplines and has consequently multiple meanings, including plasmonic nanoparticles and various nanosized metallic structures. Therefore alternative names have been given, although they are at the moment supported only by a fraction of the scientific community quantum clusters [26], nanodots [27], metal quantum dots [25] and superatoms [28]. 

S. Foteinopoulou, J. P. Vigneron, and C. Vandenbem. Optical near-field excitations on plasmonic nanoparticle-based structures Optics Express, 2007, 15,4253-4267. 

There are three major components of the MAMEF technique 1) plasmonic nanoparticles (i.e., silver, gold, copper, nickel, aluminum, zinc, etc.), 2) microwaves and 3) an aqueous assay medium. TTie plasmonic nanoparticles serve as (i) a platform for the attachment of one of the biorecognition partners (anchor probes) (ii) as an enhancer of the close-proximity fluorescence signatures via surface plasmons (i.e., MEF effect) [2] and (iii) a material not heated by microwaves for the selective heating of the aqueous media with microwave energy. 

Clare SE, Halas NJ (2004) Surface-enhanced Raman scattering on tunable plasmonic nanoparticle substrates. Proc Nati Acad Sci USA 101(52) 17930-17935... 

Tong LM, Miljkovic VD, Kail M (2010) Alignment, rotation, and spinning of single plasmonic nanoparticles and nanowires using polarization dependent optical forces. Nano Lett 10(l) 268-273... 

PRET Plasmon resonance energy transfer Similar to SERS, plasmon resonance energy transfer (PRET) between biomolecules and the plasmonic nanoparticles that they are adsorbed to allows for detection of biomolecules without appending a fluorophore. This approach yields a considerably higher sensitivity than previously known techniques in addition to spatial resolution amenable for in vivo assays. 

Lal, S., Grady, N.K., Goodrich, G.P., and Halas, N.J. (2006) Profiling the near field of a plasmonic nanoparticle with Raman-based molecular rulers. Nano Letters, 6, 2338-2343. 

Fong, K.E., Yung, L.Y.L., 2013. Localized surface plasmon resonance a unique property of plasmonic nanoparticles for nucleic acid detection. Nanoscale 5 (24), 12043—12071. 

In the following sections we describe the use and implementation of a plasmonic nanoparticle-based oxidative stress sensor in physiological conditions coupled to a sensitive optical detection modality suitable for in vitro and in vivo study use. 

S. Khatua, P. Manna, W.S. Chang, A. Tcherniak, E. Friedlander, E.R. Zubarev, S. Link, Plasmonic nanoparticles-liquid crystal composites. J. Phys. Chem. C 114, 7251-7257 (2010)... 

The plasmonic ELISA links the color of plasmonic nanoparticles to the presence or absence of the analyte. The assay uses enzymes to control the particle synthesis for generating plasmonic particles with different sizes [65,66], which exhibit distinct solution colors caused by different localized SPR. In one of the demonstrations that utilize p24 as the target analyte, the assay incorporates catalase to regulate the hydrogen peroxide concentration. 

Lublow M, Kubala S, Veyan J-F, Chabal YJ (2012) Colored porous silicon as support for Plasmonic nanoparticles. J Appl Phys 111 084-302... 

Akimov, Yuriy A., and Wee Shing Koh. Design of Plasmonic Nanoparticles for Efficient Subwavelength Trapping in Thin-Film Solar Cells. Plas-monics 6 (2010) 155-161. This paper describes how solar cells may be made thinner and lighter by the addition of aluminum nanoparticles on a surface layer of indium tin oxide to enhance light absorption. 

The localized surface plasmon resonance of individual plasmonic nanoparticles depends heavily on the size and shape of each nanoparticle. For instance, the wavelength of the dipolar surface plasmon red shifts with the increase of particle size. However, for much larger nanoparticles new bands for some multipolar modes will appear in the short-wavelength range, while the dipolar band at long-wavelength will be damped. Typically, the size of Au or Ag nanoparticles synthesized for SERS should be less than 150 nm, and larger than 20 nm. 

Figure 2.31 shows two typical stmctures for superabsorbers. The bottom one represents an ordered array of plasmonic nanoparticles on dielectric. The shape of the nanoparticle array may be rectangular, circular, etc. [230] The top stmcture represent a 2D array of nanoholes in the top metal sheet [231]. In both cases dielectric is located on a continuous metal sheet. 

A SPP is confined to the interface between the positive and the negative permittivity part and is evanescent away from the interface. SPPs can be propagating along the interface, or they can be nonpropagating, i.e., spatially confined to, e.g., a plasmonic nanoparticle (localized surface plasmons polaritons) [243]. 

As the simplest nanoantennas, plasmonic nanoparticles can be utilized to enhance the absorption within thin-film solar cells [243]. They couple incoming waves with the localized SPP field, have increased scattering cross-section and strongly localize electromagnetic field just in the thin active region of the detector. Fig. 2.62. The same principle is applicable for infrared detection [321]. This cannot be done with pure noble metal nanoparticles since their surface plasmon resonance is in ultraviolet or visible part of the spectrum. Because of that their response must be redshifted. In this part, two approaches to such redshifting are described. 

As Fig. 2.62 shows, the scattering cross-section of a plasmonic nanoparticle is greatly enhanced by plasma resonance. It can readily reach an order of magnitude value larger than the geometrical cross-section. The scattering cross-section for plasmonic nanoparticles at a wavelength X can be calculated as [322]... 

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