Optical Properties of Metal Clusters

Крейбиг, У.; Vollmer, Michael

doi:10.1007/978-3-662-09109-8

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“…2,36 At the same time, with increasing nanosphere diameter, the relative contribution of scattering to the total extinction C sca /C abs increases as seen from Figure 6a. The magnitude of the extinction increases linearly with the total nanoshell size R 2 as seen from the plot in Figure 5b and rapidly with the effective radius r eff in the case of nanorods ( Figure 5d).…”

Section: Resultsmentioning

confidence: 74%

“…16 The strongly enhanced absorption and scattering of metal nanoparticles as compared to polystyrene nanospheres or dyes is attributable to the well-known surface plasmon oscillation of electrons of the metal nanoparticle. 2,36 Silica-Gold Nanoshells. Calculated spectra of Q abs , Q sca , and Q ext for various dimensions of the silica-gold nanoshells (i.e., R 1 ) 40 nm R 2 ) 70 nm, R 1 ) 50 nm R 2 ) 70 nm, R 1 ) 60 nm R 2 ) 70 nm, R 1 ) 90 nm R 2 ) 105 nm, R 1 ) 120 nm R 2 ) 140 nm, and R 1 ) 120 nm R 2 ) 155 nm) are shown in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] Superior optical properties, coupled with recent advances in nanoparticle synthesis, 4 conjugation, 5 and assembly, 6 have stimulated interest in the use of plasmon-resonant nanoparticles and nanostructures for optical and photonic applications 7,8 and, more recently, for biomedical applications. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Nanoparticles composed of gold offer, in addition to their enhanced absorption and scattering, good biocompatibility, facile synthesis, 4 and conjugation to a variety of biomolecular ligands, antibodies, and other targeting moieties, 5 making them suitable for use in biochemical sensing and detection, 9-11 medical diagnostics, and therapeutic applications.…”

Section: Introductionmentioning

confidence: 99%

“…Optical properties of gold nanoparticles can thus be readily tuned by varying their size and shape. 1,2,[32][33][34] In addition, Halas and co-workers have shown that the use of composite nanoparticles based on a core-shell morphology (e.g., silica-gold nanoshells) allows optical tunability by variation in the composition. 35 There have been several experimental reports 2,36 on the optical properties of metal nanoparticles, including gold nanospheres, 33,34,[36][37][38][39][40][41][42] nanorods, 33,34,36,43 and nanoprisms, 44 silver nanospheres, 36,37,39,[45][46][47] nanowires, 48 and nanoprisms, [49][50][51][52] copper nanospheres, 37,45,53 aluminum nanospheres, 36 bimetallic nanoparticles, 54,55 composite nanoparticles with a core-shell structure, 35,[56][57][58][59][60] and nanoparticle chains and assemblies.…”

Section: Introductionmentioning

confidence: 99%

“…[61][62][63] At the same time, well-established theoretical tools based on the Mie theory 64 and the discrete dipole approximation (DDA) 65 method have been readily exploited for a quantitative study of the nanoparticle optical properties of different size, shape, composition, and aggregation state, etc. 2,36,[66][67][68][69][70][71][72][73] In this paper, we use Mie theory and the DDA method to calculate the absorption and scattering efficiencies and optical resonance wavelengths of gold nanospheres, silica-gold nanoshells, and gold nanorods, for various nanoparticle dimensions, so as to aid the selection of nanoparticles for specific biomedical applications. The calculated optical cross-sections of all three nanoparticle classes are found to be a few orders of magnitude higher than those for conventionally used absorbing and fluorescent dyes.…”

Section: Introductionmentioning

confidence: 99%

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Calculated Absorption and Scattering Properties of Gold Nanoparticles of Different Size, Shape, and Composition: Applications in Biological Imaging and Biomedicine

et al. 2006

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The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica-gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed (∼40 nm) show an absorption cross-section 5 orders higher than conventional absorbing dyes, while the magnitude of light scattering by 80-nm gold nanospheres is 5 orders higher than the light emission from strongly fluorescing dyes. The variation in the plasmon wavelength maximum of nanospheres, i.e., from ∼520 to 550 nm, is however too limited to be useful for in vivo applications. Gold nanoshells are found to have optical cross-sections comparable to and even higher than the nanospheres. Additionally, their optical resonances lie favorably in the near-infrared region. The resonance wavelength can be rapidly increased by either increasing the total nanoshell size or increasing the ratio of the core-toshell radius. The total extinction of nanoshells shows a linear dependence on their total size, however, it is independent of the core/shell radius ratio. The relative scattering contribution to the extinction can be rapidly increased by increasing the nanoshell size or decreasing the ratio of the core/shell radius. Gold nanorods show optical cross-sections comparable to nanospheres and nanoshells, however, at much smaller effective size. Their optical resonance can be linearly tuned across the near-infrared region by changing either the effective size or the aspect ratio of the nanorods. The total extinction as well as the relative scattering contribution increases rapidly with the effective size, however, they are independent of the aspect ratio. To compare the effectiveness of nanoparticles of different sizes for real biomedical applications, size-normalized optical cross-sections or per micron coefficients are calculated. Gold nanorods show per micron absorption and scattering coefficients that are an order of magnitude higher than those for nanoshells and nanospheres. While nanorods with a higher aspect ratio along with a smaller effective radius are the best photoabsorbing nanoparticles, the highest scattering contrast for imaging applications is obtained from nanorods of high aspect ratio with a larger effective radi...

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Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calculated Absorption and Scattering Properties of Gold Nanoparticles of Different Size, Shape, and Composition: Applications in Biological Imaging and Biomedicine

et al. 2006

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Laser-deposited silver island films: an investigation of their structure, optical properties and SERS activity

Vogel¹,

Kiefer²,

Deckert³

et al. 1998

J. Raman Spectrosc.

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Correlation between linear optical constants and Raman enhancement in phthalocyanine thin solid films with incorporated silver clusters

Linss

Stenzel

Zahn

1999

J. Raman Spectrosc.

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Surface-enhanced Raman spectroscopic (SERS) experiments on thin films of free base phthalocyanine (H 2 Pc)with embedded silver clusters are reported. The thin films were produced by thermal evaporation of H 2 Pc together with different amounts of silver (8, 15 and 26 vol.%). From transmission electron microscopy it turned out that the average silver cluster diameter changes from approximately 4 to 7 nm with increasing silver concentration. The plasmon wavenumber of the silver clusters was obtained from spectrophotometric measurements and was close to 22 000 cm −1 (approximately 450 nm), nearly independent of the silver filling factor. Raman spectra of H 2 Pc were recorded at two different exciting laser wavelengths (441.6 and 568.2 nm), being either close to or well separated from the plasmon resonance. The intensity of the Raman scattering increased with increasing silver filling factor in the films, while the lineshape of the Raman spectra was not seriously influenced by the cluster incorporation. A systematic correlation between the intensity of the plasmon absorption line and the Raman enhancement could be established and is discussed in terms of an electromagnetic enhancement mechanism.

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Optical Properties of Metal Clusters

Cited by 6,914 publications

References 0 publications

Calculated Absorption and Scattering Properties of Gold Nanoparticles of Different Size, Shape, and Composition: Applications in Biological Imaging and Biomedicine

Calculated Absorption and Scattering Properties of Gold Nanoparticles of Different Size, Shape, and Composition: Applications in Biological Imaging and Biomedicine

Laser-deposited silver island films: an investigation of their structure, optical properties and SERS activity

Correlation between linear optical constants and Raman enhancement in phthalocyanine thin solid films with incorporated silver clusters

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