Webinar on May 26, 2021, 3:45 pm UTC+2

Probing Nanoscale Temperature Differences Among Nanoparticle Assemblies with Wavelength-Dependent Photothermal Imaging

The ability to control and manipulate temperature at nanoscale dimensions has the potential to impact several applications such as heat-assisted magnetic recording, photothermal therapies, and temperature-driven chemical reactivity. To achieve nanoscale temperature control, one challenge that must be overcome is the need to mitigate heat diffusion, such that the temperature only changes in well-defined nanoscopic regions of the sample. In collaboration with theory provided by the Masiello group (University of Washington), we have demonstrated the ability to use far-field laser excitation to shape the thermal near-field in individual gold nanorod heterodimers and trimers by resonantly pumping different hybridized plasmon modes. Specifically, we observe changes in the point spread function of photothermal images as the pump wavelength is tuned. Through comparison with numerical simulations, the underlying thermal gradients within the nanorod assemblies are revealed as a function of selective coupled plasmon mode excitation.