Interband transition probing of coherent acoustic phonons of gold/metal oxide core–shell nanoparticles

Lijie Wang, Malte Oppermann, Michele Puppin, Benjamin Bauer, Tsz Him Chow, Jianfang Wang, Majed Chergui

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We present ultrafast spectroscopic investigations of the coherent acoustic vibrations of Au/SiO2 and Au/TiO2 core–shell nanoparticles (NPs) upon excitation of the Au surface plasmon resonance. The oscillations are detected in the region of the interband transitions of Au in the deep-ultraviolet, where they appear in the form of intensity modulations with no changes in the spectra. For the Au/SiO2 NPs, the oscillation period (typically ∼10 ps) is similar to that of bare Au NPs having a size identical to that of the core, implying a negligible coupling of the core with the shell. For Au/TiO2 NPs, significantly slower (∼20 ps) oscillations appear, whose period is identical to that of a bare gold NP having the same total diameter, implying that the Au/TiO2 NPs can be treated as a single object. This may due to the strong chemical interaction at the gold/TiO2 interface. Finally, the amplitude modulations are a consequence of the modifications of the band structure of the Au NP, resulting from the strain due to the phonons, which may affect the joint density of states.
Original languageEnglish (US)
Pages (from-to)082201
JournalApplied Physics Letters
Volume122
Issue number8
DOIs
StatePublished - Feb 21 2023

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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