Early stages of hot-electron thermalization in small gold nanoparticles wrapped in an adsorbates shell have been investigated by femtosecond transient absorption spectroscopy. Type-I hot electrons thermalize in 800 fs (to form type-II hot electron) either by scattering with cold conduction band electrons or by chemical interface scattering with adsorbates shell. Type-II hot electrons redistribu...

the main objective of this research was to synthesize and characterize gold-coated fe3o4 /sio2 nanoshells for clinical applications. magnetite nanoparticles (nps) were prepared via co-precipitation. the results showed that smaller particles can be synthesized by decreasing the naoh concentration, which in our case this corresponded to 35 nm by using 0.9 m of naoh at 750 rpm. the nps were then m...

The present study reports a novel concept of a direct solar thermal collector that harnesses the localized surface plasmon of metallic nanoparticles suspended in water. At the plasmon resonance frequency, the absorption and scattering from the nanoparticle can be greatly enhanced via the coupling of the incident radiation with the collective motion of electrons in metal. However, the surface pl...

Colloidal gold nanoparticles are a widespread nanomaterial with many potential applications, but their aggregation in suspension is a critical issue which is usually prevented by organic surfactants. This solution has some drawbacks, such as material contamination and modifications of its functional properties. The gold nanoparticles presented in this work have been synthesized by ultra-fast la...

Switchable surface redox chemistry is demonstrated in gold@iron/iron oxide core-shell nanoparticles with ambient oxidation and plasmon-mediated reduction to modulate the oxidation state of shell layers. The iron shell can be oxidized to iron oxide through ambient oxidation, leading to an enhancement and red-shift of the gold surface plasmon resonance (SPR). This enhanced gold SPR can drive redu...

We report on the role of plasmonic resonances in determining the delicate balance between scattering and absorption of light in nanometric particle arrays applied to the front surface of solar cells. Strong parasitic absorption is shown to be dependent upon the excitation of localized surface plasmon resonances and prohibits efficient scattering into the underlying semiconductor. Via detailed a...

There have been few fundamental improvements in clinical X-ray contrast agents in more than 25 years, and the chemical platform of tri-iodobenzene has not changed. Current agents impose serious limitations on medical imaging: short imaging times, the need for catheterization in many cases, occasional renal toxicity, and poor contrast in large patients. This report is the first demonstration tha...

Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetitio...

The nonlinear optical properties of four metallic (Au-, Au/Ag-, Ag-, and Pt-) nanoparticle suspensions in toluene have been studied in both femtosecond and nanosecond regimes. Nonlinear transmission measurements in the femtosecond laser regime revealed two-photon absorption (2PA) induced nonlinear attenuation, while in the nanosecond laser regime a stronger nonlinear attenuation is due to both ...