Chemically-Controlled Ultrafast Photothermal Response in Plasmonic Nanostructured Assemblies

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Plasmonic nanoparticles efficiently convert light to heat through resonant absorption and hot carrier generation.
• Nanoparticle assemblies (suprastructures) can exhibit enhanced photothermal properties due to collective effects.
• Controlling nanoparticle assembly architecture is key to optimizing photothermal conversion.

Purpose of the Study:

• To investigate the photothermal conversion dynamics and nonlinear optical response of water-soluble nanoeggs.
• To explore the influence of gold core size on the photothermal performance of these nanoegg assemblies.
• To compare the heating efficiency of nanoeggs with conventional, unstructured nanoheaters.

Main Methods:

• Fabrication of water-soluble nanoeggs (Au nanocrystal assembly within ferrite nanocrystal shell).
• Ultrafast pump-probe spectroscopy to analyze photothermal dynamics from picoseconds to nanoseconds.
• Semiclassical modeling to understand hot-carrier photogeneration and matrix ligand heating.

Main Results:

• Nanoegg photothermal properties can be precisely tuned by controlling the gold suprastructure core size.
• Nanoeggs exhibit superior photothermal performance, including higher peak temperatures and faster thermalization.
• The collective plasmonic effects in the nanoegg assembly enhance heating efficiency compared to unstructured nanoparticles.

Conclusions:

• The nanoegg architecture provides a platform for designing and tailoring efficient photothermal nanoheaters.
• Controlling core size offers a method to optimize heat generation and dissipation in plasmonic assemblies.
• These findings suggest potential applications for advanced photothermal therapies and nanoscale heating.