AuPd Metal Nanoparticles as Probes of Nanoscale Thermal Transport in Aqueous Solution

At the level of individual molecules, familiar concepts of heat transport no longer apply. When large amounts of heat are transported through a molecule, a crucial process in molecular electronic devices, energy is carried by discrete molecular vibrational excitations. We studied heat transport through self-assembled monolayers of long-chain hydrocarbon molecules anchored to a gold substrate by ultrafast heating of the gold with a femtosecond laser pulse. When the heat reached the methyl groups at the chain ends, a nonlinear coherent vibrational spectroscopy technique detected the resulting thermally induced disorder. The flow of heat into the chains was limited by the interface conductance. The leading edge of the heat burst traveled ballistically along the chains at a velocity of 1 kilometer per second. The molecular conductance per chain was 50 picowatts per kelvin.H eat transport is central to the operation of mechanical and electronic machinery, but at the level of individual molecules, the familiar concepts of heat diffusion by phonons in bulk materials no longer apply. Heat is transported through a molecule by discrete molecular vibrations. An emerging area in which vibrational energy transfer becomes crucial is the field of molecular electronics, where longchain molecules attached to tiny electrodes are used to transport and switch electrons. When an electron is transported through a molecule, a portion of the electron's kinetic energy can be lost, appearing as molecular vibrational energy (1). In studies such as this one, in which molecular energy levels are not individually resolved, it is conventional to call such processes "heat dissipation" or "nanoscale thermal transport" (2), even though an equilibrium Boltzmann distribution is not necessarily achieved. Nitzan and co-workers (3) have estimated that 10 to 50% of the electron energies could be converted to heat, so that a power of 10 11 eV/s may be dissipated on a molecular electronic bridge carrying 10 nA under a bias of 1 eV. Using classical and quantum mechanical methods, they and others (1) have calculated steadystate temperatures resulting from such dissipation. Steady-state calculations, however, do not entirely capture the essence of this phenomenon. The energy lost when electrons are transported through a molecular wire in a fraction of a picosecond appears as staccato bursts, up to 1 eV per burst. On a 10-carbon alkane molecule, for instance, 1eV is enough energy to produce a transient temperature jump DT ≈ 225 K. At the temperatures associated with these ultrafast energy bursts, Nitzan and coworkers (3) suggest that, instead of the usual phonon mechanisms prevalent in ordinary thermal conduction processes (1), much of the heat is carried by higher-energy molecular vibrations such as carbon-carbon bending and stretching and carbon-hydrogen bending, which are delocalized over a few carbon segments (3).To study molecular energy transport in the regime of short distances, short time intervals, and large temperature bursts, we have used an ultr...

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“…This value of G is similar to what was previously obtained in studies of SAM-decorated nanoparticles in aqueous solutions (15).…”

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confidence: 89%

Ultrafast Flash Thermal Conductance of Molecular Chains

Wang

Carter

Lagutchev

et al. 2007

Science

Self Cite

419

527

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“…1). As in some previous works involving colloidal solutions, 9,12 modeling of the cooling kinetics of our glass-embedded metal nanoparticles was performed taking into account both effects. The electron and lattice temperatures in a nanoparticle have been assumed to be well-defined and identical (to T p ).…”

Section: Discussionmentioning

confidence: 99%

“…1), it thus contains information on the former process, i.e., on the Kapitza thermal resistance at the particle-matrix interface. [8][9][10][11][12][13] Most previous experiments were carried out in colloidal solutions of metal nanoparticles, and have addressed the impact of nanoparticle size, 8 solvent composition, 9 and interface layer (e.g., using nanoparticles encapsulated in a silica or polymeric shell 11,13 ). In spite of their technological interest, only few experiments were reported on nanoparticles embedded in a solid matrix.…”

Section: Introductionmentioning

confidence: 99%

Cooling dynamics and thermal interface resistance of glass-embedded metal nanoparticles

Juvé

Scardamaglia²,

Maioli³

et al. 2009

Phys. Rev. B

133

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The cooling dynamics of glass-embedded noble metal nanoparticles with diameters ranging from 4 to 26 nm were studied using ultrafast pump-probe spectroscopy. Measurements were performed probing away from the surface plasmon resonance of the nanoparticles to avoid spurious effects due to glass heating around the particle. In these conditions, the time-domain data reflect the cooling kinetics of the nanoparticle. Cooling dynamics are shown to be controlled by both thermal resistance at the nanoparticule-glass interface, and heat diffusion in the glass matrix. Moreover, the interface conductances are deduced from the experiments and found to be correlated to the acoustic impedance mismatch at the metal/glass interface.2

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“…It has been demonstrated experimentally that an interface resistivity at the gold/water interface exists and can play a significant role in the heat release. [38][39][40][41] The interface resistivity can reach appreciable values when the liquid does not wet the solid. The wetting depends on the nature of the interface, and in particular a possible molecular coating.…”

Section: A Physical Systemmentioning

confidence: 99%

Femtosecond-pulsed optical heating of gold nanoparticles

2011

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We investigate theoretically and numerically the thermodynamics of gold nanoparticles immersed in water and illuminated by a femtosecond-pulsed laser at their plasmonic resonance. The spatiotemporal evolution of the temperature profile inside and outside is computed using a numerical framework based on a Runge-Kutta algorithm of the fourth order. The aim is to provide a comprehensive description of the physics of heat release of plasmonic nanoparticles under pulsed illumination, along with a simple and powerful numerical algorithm. In particular, we investigate the amplitude of the initial instantaneous temperature increase, the physical differences between pulsed and cw illuminations, the time scales governing the heat release into the surroundings, the spatial extension of the temperature distribution in the surrounding medium, the influence of a finite thermal conductivity of the gold/water interface, the influence of the pulse repetition rate of the laser, the validity of the uniform temperature approximation in the metal nanoparticle, and the optimum nanoparticle size (around 40nm) to achieve maximum temperature increase.

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AuPd Metal Nanoparticles as Probes of Nanoscale Thermal Transport in Aqueous Solution

Cited by 137 publications

References 29 publications

Ultrafast Flash Thermal Conductance of Molecular Chains

Ultrafast Flash Thermal Conductance of Molecular Chains

Cooling dynamics and thermal interface resistance of glass-embedded metal nanoparticles

Femtosecond-pulsed optical heating of gold nanoparticles

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