Aligned Gold Nanorods in Silica Made by Ion Irradiation of Core–Shell Colloidal Particles

Roorda, S.; Dillen, T. van; Polman, A.; Gräf, Christina; Blaaderen, Alfons van; Kooi, Bart J.

doi:10.1002/adma.200305742

Cited by 148 publications

(123 citation statements)

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“…As the macroscopic stress generated from SHI irradiation in planar constrained films can reach values as large as several hundreds of megapascal, we suggest that mechanism ͑iii͒ can participate to the evolution of the NPs. It should be mentioned that this scenario has already been proposed by Roorda et al 13 to explain the shape change of Au NPs that are confined within a silica shell and assumed to be solid. However, as pointed out by Klaumünzer,16 this indirect mechanism alone is not sufficient to account for the observed deformation of solid NPs; i.e., the metallic NP must actively participate in the deformation process.…”

Section: ͑I͒mentioning

confidence: 96%

“…A detailed investigation of the irradiation-induced deformation has been carried out by Polman's group for NPs with a hybrid structure, viz., a Au-core/silica-shell ͑Au@ SiO 2 ͒ system. [13][14][15] The authors observed that during irradiation with MeV ions ͑4-30 MeV͒, the silica shell turns into an oblate ellipsoidal shape with its main axis perpendicular to the beam direction, while the Au core elongates along the ion beam, provided the silica-shell thickness is large enough ͑Ͼ20 nm͒. This indicates that the deformation of the metal core is somehow related to ion-induced effects in the silica shell.…”

Section: Introductionmentioning

confidence: 99%

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Ion beam shaping of Au nanoparticles in silica: Particle size and concentration dependence

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Rizza

Mink

et al. 2009

Journal of Applied Physics

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Irradiation with swift heavy ions of spherical Au nanoparticles confined within a silica matrix shapes them into prolate nanorods and nanowires whose principal axes are aligned along the beam direction. In the present paper, we investigate the role that is played by the initial nanoparticle size and concentration in this so-called ion-shaping mechanism. We have produced silica films wherein Au nanoparticles with average diameters of 15, 30, and 45 nm were embedded within a single plane and have irradiated these films at 300 K at normal incidence with 18, 25, and 54 MeV Ag ions. We demonstrate the existence of both threshold and saturation fluences for the elongation effects mentioned. The values of these critical fluences depend both on the ion energy and the initial nanoparticle size. Moreover, we show that 45 nm Au particles are not deformed when irradiated with 18 MeV Ag ions, such that this value corresponds to an energy threshold for the deformation process. As far as the influence of the nanoparticle concentration on the shaping characteristics is concerned, we have found that above the critical irradiation fluence, the deformation effect becomes very sensitive to the initial concentration of the nanoparticles.

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Section: ͑I͒mentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Ion beam shaping of Au nanoparticles in silica: Particle size and concentration dependence

Dawi

Rizza

Mink

et al. 2009

Journal of Applied Physics

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“…Freestanding metallic NPs irradiated under comparable conditions do not change shape, demonstrating the embedding a-SiO 2 matrix must have a role in the shape transformation process [8,17]. An unambiguous identification of the atomistic mechanism underlying the transformation remains lacking but a metal NP melt-and-flow process, the latter potentially as a means of relieving in-plane stress within the matrix [8,14,17], is certainly plausible. For this report, we examine the SHII-induced elongation of ten embedded, elemental metal NP systems using a common irradiation condition to enable the identification of subtle, metal-specific differences and demonstrate that the thermodynamic properties of both the matrix and metal are intrinsic to the shape transformation process.…”

mentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14][15][16][17] citing selected examples. Freestanding metallic NPs irradiated under comparable conditions do not change shape, demonstrating the embedding a-SiO 2 matrix must have a role in the shape transformation process [8,17]. An unambiguous identification of the atomistic mechanism underlying the transformation remains lacking but a metal NP melt-and-flow process, the latter potentially as a means of relieving in-plane stress within the matrix [8,14,17], is certainly plausible.…”

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confidence: 99%

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Role of Thermodynamics in the Shape Transformation of Embedded Metal Nanoparticles Induced by Swift Heavy-Ion Irradiation

et al. 2011

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Swift heavy-ion irradiation of elemental metal nanoparticles (NPs) embedded in amorphous SiO 2 induces a spherical to rodlike shape transformation with the direction of NP elongation aligned to that of the incident ion. Large, once-spherical NPs become progressively more rodlike while small NPs below a critical diameter do not elongate but dissolve in the matrix. We examine this shape transformation for ten metals under a common irradiation condition to achieve mechanistic insight into the transformation process. Subtle differences are apparent including the saturation of the elongated NP width at a minimum sustainable, metal-specific value. Elongated NPs of lesser width are unstable and subject to vaporization. Furthermore, we demonstrate the elongation process is governed by the formation of a molten ion-track in amorphous SiO 2 such that upon saturation the elongated NP width never exceeds the molten ion-track diameter. Ion-solid interactions during swift heavy-ion irradiation (SHII) are dominated by inelastic processes in the form of electron excitation and ionization while, in contrast, the influence of elastic processes such as ballistic displacements is negligible. Macroscopically, amorphous SiO 2 (a-SiO 2 ) undergoes a volume-conserving anisotropic deformation when subjected to SHII such that thin freestanding layers contract and expand, respectively, in directions parallel and perpendicular to that of the incident ion [1]. The viscoelastic model [2,3], based on a transient thermal effect, successfully explains this so-called ion hammering. Microscopically, energy is deposited along the ion path, from incident ion to matrix electrons, and is then dissipated within a narrow cylinder of material surrounding the ion path. The heat flow in both the electron and lattice subsystems is well described as functions of time and radial distance by the inelastic thermal spike (i-TS) model [4,5]. When the temperature of the lattice exceeds that required for melting, the material along the ion path is molten and upon quenching an ion track is formed. Recently, we measured the molten ion-track diameter in a-SiO 2 as a function of electronic stopping power [6]. The ion-track radial density distribution consisted of an under-dense core and over-dense shell (relative to unirradiated material), the formation of which was attributed to a quenched-in pressure wave emanating from the ion-track center [6].Elemental metal nanoparticles (NPs) embedded in a-SiO 2 and subjected to SHII can undergo an intriguing shape transformation where once-spherical NPs become progressively more rodlike with the direction of elongation aligned along that of the incident ion. This phenomenon has been reported for several metals under a wide range of SHII conditions, with Refs. [7][8][9][10][11][12][13][14][15][16][17] citing selected examples. Freestanding metallic NPs irradiated under comparable conditions do not change shape, demonstrating the embedding a-SiO 2 matrix must have a role in the shape transformation process [8,17]. An unambiguous ...

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Angle‐Dependent Extinction of Anisotropic Silica/Au Core/Shell Colloids Made via Ion Irradiation

et al. 2005

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Aligned Gold Nanorods in Silica Made by Ion Irradiation of Core–Shell Colloidal Particles

Cited by 148 publications

References 12 publications

Ion beam shaping of Au nanoparticles in silica: Particle size and concentration dependence

Ion beam shaping of Au nanoparticles in silica: Particle size and concentration dependence

Role of Thermodynamics in the Shape Transformation of Embedded Metal Nanoparticles Induced by Swift Heavy-Ion Irradiation

Angle‐Dependent Extinction of Anisotropic Silica/Au Core/Shell Colloids Made via Ion Irradiation

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