Ultrasonic relaxation acoustic resonator

Walther, K. (1967). Ultrasonic relaxation at the Neel temperature and nuclear acoustic resonance in MnTe, Solid State Communications, 5 (5), pp. 399. 

The optoacoustic properties of plasmon-resonant gold nanoparticles originate from photoinduced cavitation effects. This process can be summarized as follows (i) thermalization of conduction electrons on the subpicosecond timescale/ (ii) electron-phonon relaxation on the picosecond timescale and thermalization of the phonon lattice, with a subsequent rise in temperature by hundreds to thousands of degrees (iii) transient microbubble expansion upon reaching the kinetic spinodal of the superheated medium, initiated on the nanosecond timescale (iv) microbubble collapse, resulting in shockwaves and other forms of acoustic emission. The expansion and collapse of a cavitation bubble takes place on a microsecond timescale, and are easily detected by ultrasonic transducers. 

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