The thermal conductivity and heat capacity of surfactant and polyelectrolyte coatings of gold nanorods (GNRs) in aqueous solution are investigated by transient absorption, following femtosecond pumping of the longitudinal localized surface plasmons. Surfactant and polyelectrolyte layer thicknesses are measured by dynamic light scattering (DLS). The GNRs are initially coated with a bilayer of the quaternary ammonium surfactant cetyltrimethylammonium bromide (CTAB). The rate of change of the absorption of gold nanorods in aqueous solution varies with the probe laser wavelength due to the shift in the plasmon resonance created by heating of media around the particles. The cooling dynamics of gold nanorods are best measured by tuning the pump-probe laser wavelength to the absorption peak of the sample. The heat capacity of the surfactant layer is 2.0 ± 0.3 J cm(-3) K(-1); the thermal conductivity of the surfactant layer drops from 0.24 to 0.18 W m(-1) K(-1) at solution concentrations above the CTAB critical micelle concentration (cmc). Layer-by-layer polyelectrolyte coatings using poly(acrylic acid) (PAA) and polyallyamine hydrochloride (PAH) increase the thermal conductivity and heat capacity of the surface layer. PAH-terminated layers have increased thickness, thermal conductivity, and heat capacity relative to PAA-terminated layers; this effect is attributed to greater water penetration into PAH-terminated surface layers.

We report experimental studies of heat transport for a system of Au nanorods immobilized on a crystalline quartz support and immersed in various organic fluids. The Au nanorods are abruptly heated by a subpicosecond optical pulse; the cooling of the Au nanorods is monitored by transient absorption. We analyze the data using a three-dimensional model that describes heat flow between the nanorod and fluid with an additional interface thermal conductance added to account for heat transport between the Au nanorods and the high thermal conductivity support. For methanol, ethanol, toluene, and hexane, the thermal conductance of the nanorod/fluid interface falls within a narrow range: 36 ± 4 MW m −2 K −1 for methanol, 32 ± 6 MW m −2 K −1 for ethanol, 30 ± 5 MW m −2 K −1 for toluene, and 25 ± 4 MW m −2 K −1 for hexane.

We report experimental studies of interfacial heat transport for a system of Au nanodisks supported on fused silica substrates, coated by hydrophilic and hydrophobic self-assembled monolayers, and immersed in water−ethanol mixtures and solutions of a nonionic surfactant, hexyl-β-Dglucoside in water. The Au nanodisks are abruptly heated by a subpicosecond optical pulse; time-resolved changes in the temperature of the Au nanodisk and the liquid near the nanodisk/liquid interface are monitored by measurements of transient changes in optical transmission. The interface thermal conductance G of nanodisks coated with a hydrophilic self-assembled monolayer (SAM) of sodium 3-mercapto-1propanesulfonate varies over the range 90 < G < 190 MW m −2 K −1 as the composition of the liquid mixture is changed from pure ethanol to pure water. With increasing hexyl-β-D-glucoside concentration in water, the interface thermal conductance of hydrophilic nanodisks decreases from 190 MW m −2 K −1 to 130 MW m −2 K −1 as the concentration is varied between pure water and 100 mM glucoside. For hydrophobic surfaces, G = 70 ± 10 MW m −2 K −1 . We relate changes in thermal conductance to changes in work of adhesion.

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Effect of local electrical properties on the electrostatic discharge withstand capability of multilayered chip ZnO varistors J. Appl. Phys.