Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 30: Poster II
DY 30.26: Poster
Donnerstag, 29. März 2007, 16:00–18:00, Poster D
Bubble dynamics on laser excited nanoparticles — •Anton Plech1, Vassilios Kotaidis1, Michael Wulff2, Gero von Plessen3, and Christian Dahmen3 — 1Fachbereich Physik, Uni Konstanz, Universitätsstr. 10, D-78457 Konstanz — 2ESRF, BP 220, F-38043 Grenoble — 3I. Physikalisches Institut der RWTH Aachen, Huyskensweg, D-52074 Aachen
Strong nonequilibrium exitation of gold nanoparticles can be achieved by femtosecond laser heating. The nanoscale provides cooling rates of 1013 K/sec in aqueous suspension. Consequently the phase transition in the adjacent water layer is of explosive nature with strong supersaturation. We have employed a pump-probe technique using femtosecond laser pulses as heat stimulus and pulsed x-rays as probe for the nanoscale structure relaxations. By a combination of x-ray techniques it was possible to measure the particle temperature, pressure transients in the water phase, vapor bubble morphology and particle shape. Bubbles forming around 9 nm particles expand to sizes in the 20 nm range before they recollapse within a subnanosecond interval. The bubble dynamics can be modelled by macroscopic fluid dynamics (Rayleigh Plesset equation) [1]. We found a supersaturation of the water phase to 85
[1] V. Kotaidis, A. Plech: Cavitation dynamics on the nanoscale, Appl. Phys. Lett., 84 (2005) 213102.
[2] V. Kotaidis, C. Dahmen, G. von Plessen, F. Springer, A. Plech: Excitation of nanoscale vapor bubbles at the surface of gold nanoparticles in water, J. Chem. Phys., 124, (2006) 184702.