The formation and relaxation of plasmon-induced hot electrons in Au nanodisks (AuNDs) with relatively large particle size was studied by femtosecond pump-probe spectroscopy. We temporally resolved the plasmon-induced formation of nonthermal electrons through intraband transitions and subsequent redistribution of nonthermal electrons to thermal electrons. The transient extinction spectra were found to exhibit clear dichroism for the pump polarization on a time scale of a few hundred femtoseconds. The electric field distribution was calculated using the Finite-difference time-domain (FDTD) method to be inhomogeneous inside the AuNDs under irradiation by linearly polarized light. The formation and relaxation of hot electrons occur locally inside the AuNDs, which results in the observed ultrafast dichroic response.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering