On the temperature stability of gold nanorods: comparison between thermal and ultrafast laser-induced heating

Petrova, Hristina; Juste, Jorge Pérez; Pastoriza‐Santos, Isabel; Hartland, Gregory V.; Liz‐Marzán, Luis M.; Mulvaney, Paul

doi:10.1039/b514644e

Cited by 300 publications

(375 citation statements)

References 62 publications

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“…These processes are accelerated at higher temperature. 29 We therefore attribute the dominance of blue shifts at higher temperature to melting and reshaping of the nanorods, which redistributes material from the tip to the sidewalls and thereby overcompensates the etching of the sidewalls. Indeed, reshaping of our gold nanorods deposited on glass substrates has been observed under the same excitation conditions without oxidants (see supporting information for details).…”

Section: Introductionmentioning

confidence: 95%

Enhancing Single-Nanoparticle Surface-Chemistry by Plasmonic Overheating in an Optical Trap

Lutich

et al. 2012

Nano Lett.

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Surface-chemistry of individual, optically trapped plasmonic nanoparticles is modified and accelerated by plasmonic overheating. Depending on the optical trapping power, gold nanorods can exhibit red-shifts of their plasmon resonance (i.e. increasing aspect ratio) under oxidative conditions. In contrast, in bulk exclusively blue shifts (decreasing aspect ratios) are observed. Supported by calculations, we explain this finding by local temperatures in the trap exceeding the boiling point of the solvent which can not be achieved in bulk.Keywords noble metal nanoparticles; plasmon resonance; colloidal chemistry; nano-/microfluidics; gold nanorods; plasmonic heating Miniaturization is a successful approach to faster, more efficient applications in physics and chemistry. In chemistry, the reduction of reaction volumes is expected to lead to highthroughput, portable analytical and sensing applications, and fundamental insights into single-molecule chemical reactions. [1][2][3] Lab-on-a-chip applications frequently employ microor nanofluidic structures. [4][5][6][7] However, these approaches do not change the outcome of a chemical reaction. Optical trapping on the other hand, being compatible with micro-or nanofluidic systems, is a well-established technique that has been widely applied to singlemolecule force and optical spectroscopy, non-invasive manipulation, and chemical reactions monitoring . [8][9][10][11][12][13] More recently, optical trapping has been applied to plasmonic noble metal nanoparticles. [14][15][16] Due to their localized surface plasmon resonances, noble metal nanoparticles provide strongly enhanced and highly localized electromagnetic fields close to their surface. 17 Their optical and field-enhancing properties allow for manipulating and enhancing fluorescence, Raman scattering, charge and energy transfer, and local temperature. [18][19][20][21] The surface plasmon resonances can be tuned through controlling size, shape and material of the nanoparticles via advanced colloidal chemistry. 22 Gold nanorods for instance, display two different plasmon modes: one transversal, in which the electrons oscillate perpendicular to the long axis of the rod, and the other red shifted longitudinal, in which the electrons oscillate along the long axis of the nanorod. 23 Europe PMC Funders Author Manuscripts sensitively depends on the nanorod's aspect ratio: the higher the aspect ratio, the more red shifted the longitudinal plasmon resonance.Here we apply the plasmonic heating effect of a single gold nanoparticle in an optical trap to both accelerate and modify chemical reactions on the surface of the particle. We show that individual optically trapped plasmonic particles modify and accelerate surface-chemistry by plasmonic overheating to yield different and faster results than the corresponding bulk reactions. Individual gold nanorods under oxidative conditions can display a red-shift of their localized surface plasmon resonances corresponding to an increasing aspect ratio, while in bulk exclusively bl...

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Section: Introductionmentioning

confidence: 95%

Enhancing Single-Nanoparticle Surface-Chemistry by Plasmonic Overheating in an Optical Trap

Lutich

et al. 2012

Nano Lett.

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“…It can, on the other hand, explain recent observations of other groups, showing that shape transformation in gold particles such as nanorods can take place in the same temperature interval. 8,9,39 A further point to be raised would be the time scale needed for the establishment of surface melting. A number of studies investigates the structural properties of particles upon high laser excitation.…”

Section: I(τ)mentioning

confidence: 99%

“…A similar, very recent study has shown that nanorods with a large aspect ratio of the axes can be transformed at 200°C into spheres and partial relaxation occurs much earlier (100°C). 9 Surface melting is taken as the origin for these relaxations.…”

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confidence: 99%

A Surface Phase Transition of Supported Gold Nanoparticles

et al. 2007

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A thermal phase transition has been resolved in gold nanoparticles supported on a surface. By use of asynchronous optical sampling with coupled femtosecond oscillators, the Lamb vibrational modes could be resolved as a function of annealing temperature. At a temperature of 104°C the damping rate and phase changes abruptly, indicating a structural transition in the particle, which is explained as the onset of surface melting.Metallic nanoparticles are in the focus of fundamental and applied research. They show an optical response in the visible region that depends strongly on size, shape, and local dielectric environment, 1 making them appealing for nanoscale sensor applications. The interaction with light shows interesting peculiarities, such as ultrafast relaxation dynamics, coupling to nonradiative processes, or near field enhancement. 2 In particular nanoscale gold particles have received strong attention due to their versatile synthesis protocols, 3 shape transformations, or binding to biological molecules. 4 They served also to understand the generic structural properties that scale with size or shape. The melting point depression with decreasing particle size represents one of the prominent features, arising from the change in ratio between surface and bulk atoms and the reduction in binding energy. Since the seminal publication of Buffat and Borel 5 several improvements of the description have been made, while the general relation of the melting point depression ∆T mp ∝ 1/D as a function of size D remains valid. One of these points is the existence of surface melting, i.e., a coexistence of a liquid-like layer of atoms at the surface with the solid core material at temperatures below the respective melting point. 6,7 While this effect seems to be very basic, there is still a lack of unambiguous experimental proof regarding the details, in particular for gold nanoparticles.Inasawa et al. 8 have tried to investigate the shape transformation of elongated particles on a surface induced by static heating (ex situ) and concluded that a transformation into spheres takes places at temperatures as low as 400°C. A similar, very recent study has shown that nanorods with a large aspect ratio of the axes can be transformed at 200°C into spheres and partial relaxation occurs much earlier (100°C). 9 Surface melting is taken as the origin for these relaxations.It should also be borne in mind that the relaxation of rods could also be caused by other forces, as has been shown by laser-induced melting, 10 where the onset correlates with dislocations in the interior, as the rods are subjected to a large uniaxial strain due to surface tension.Hartland et al. have also reported on several experiments, which aimed at the structural transformations on a very short time scale, initiated by femtosecond excitation. 11,12 The vibrational response of the particles has been recorded by optical pump-probe techniques, reflecting the mechanical properties of the particles. While the change of the elastic constants of the spheres ...

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“…They found that at 180 °C the nanorods coalesce into irregular shaped clusters and at 500 °C they coalesce into large spherical particles. Petrova et al investigated the differences between the bulk-and ultrafast laser-induced heating of nanorods [35]. For bulk-heating they found that at 250 °C the solidsupported nanorods were converted into spheres.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of high temperatures on bare (without inorganic shell) gold nanorods was investigated experimentally by optical heating via laser pulses [29][30][31][32][33] or annealing solid supported gold nanorods [34,35] using bulk-heating. Hu et al investigated the heating of the nanorods between 180 °C and 500 °C using bulk-annealing [34].…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

Gergely-Fülöp

Zámbó

Deák

2014

Materials Chemistry and Physics

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The effect of different temperatures (up to 900 °C) on the morphology of mesoporous silicacoated gold nanorods was systematically investigated. Gold nanorods with different aspect ratios (AR ranging from 2.5 to 4.3) were coated with a 15 nm thick mesoporous silica shell.Silicon supported monolayers of the particles were annealed in the temperature range of 300-900 °C. The resulting changes in particle morphology were investigated using scanning electron microscopy and visible wavelength extinction spectroscopy. The silica coating generally improved the stability of the nanorods from ca. 250 °C by several hundreds degree Celsius. For nanorods with AR<3 the shape and the aspect ratio change is only moderate up to 700 °C. At 900 °C these nanorods became spherical. For nanorods with AR>3, lower stability was found as the aspect ratio decrease was more significant and they transformed into spherical particles already at 700 °C. It was confirmed by investigating empty silica shells that the observed conformal change of the shell material when annealing core/shell particles is dictated by the deformation of the core particle. This also implies that a significant mechanical stress is exerted on the shell upon core deformation. In accordance with this, for the highest aspect ratio (AR~4) nanorod the shell breaks up at 900 °C and the gold cores were partially released and coalesced into large spherical particles.

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On the temperature stability of gold nanorods: comparison between thermal and ultrafast laser-induced heating

Cited by 300 publications

References 62 publications

Enhancing Single-Nanoparticle Surface-Chemistry by Plasmonic Overheating in an Optical Trap

Enhancing Single-Nanoparticle Surface-Chemistry by Plasmonic Overheating in an Optical Trap

A Surface Phase Transition of Supported Gold Nanoparticles

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

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