Acoustic damping particle

With a sensitive pump-probe technique, possibly within a common-path interferometer, one can detect the acoustic vibrations of an individual gold nanoparticle [36]. This measurement directly gives the vibration s damping time, a parameter inaccessible to measurements on ensembles of nanoparticles, because of the inhomogeneity in sizes and shapes of populations of nanoparticles. The damping of vibrations of a nanoparticle depends critically on the acoustic impedance mismatch between particle and substrate materials, as well as on the mechanical contact area between them. Acoustic damping is therefore a probe of this contact, which may often be limited to a few nanometers only in diameter. 

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