Numerical Modeling of Transient Absorption in Hybrid Dual-Plasmonic Au/CuS Nanocrystals

Colloidal hybrid Au/CuS nanocrystals have emerged as highly interesting dual-plasmonic materials. Femtosecond transient absorption spectroscopy (TAS) revealed that the resonant excitation of the localized surface plasmon resonance of either Au or CuS results in a transient response in the counterpart, which we attributed to Landau damping stemming from hot carriers at the domain interface. Here, we employ numerical modeling to further clarify the origin of the response in Au/CuS nanocrystals. Numerical simulations identify the UFO-shaped geometry of the Au/CuS nanocrystals, the anisotropy of CuS, and the plasmonic response modified by Landau damping during the TAS as the main governing mechanisms for the dual-plasmonic optical response. Our numerical approach provides an important tool for the modeling of TAS data and provides valuable insights for the design of innovative colloidal dual-plasmonic nanocrystals with optical anisotropy for applications in photocatalysis, thermoplasmonics, and ultrafast photonics.