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

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