Abstract
We demonstrate that higher-order acoustic phonon oscillations of self-assembled Au nanoparticles can be excited using higher frequency bandwidth picosecond acoustic pulses generated by superdiffusive hot electrons. These modes require directional excitations such as a longitudinal strain pulse, being inaccessible in a direct optical excitation scheme. They are detected using the periodic shift of the surface plasmon resonance and are coherently controlled by a sequence of delayed acoustic pulses. Acoustic mode calculations show that the high-frequency mode corresponds to two higher-order spheroidal modes.
- Received 27 September 2019
- Revised 27 November 2019
DOI:https://doi.org/10.1103/PhysRevB.101.020302
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