Heidelberg 2015 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 32: Interaction with strong or short laser pulses III
A 32.4: Vortrag
Donnerstag, 26. März 2015, 15:30–15:45, C/HSW
Explosion dynamics of single clusters resolved for particle size and laser power density — •D. Rupp1, L. Flückiger1, M. Adolph1, T. Gorkhover1,2, M. Krikunova1, M. Müller1, J. Müller1, T. Oelze1, Y. Ovcharenko1, M. Sauppe1, B. Röben1, S. Schorb1,2, D. Wolter1, R. Treusch3, C. Bostedt1,2, and T. Möller1 — 1TU Berlin — 2LCLS@SLAC — 3FLASH@DESY
Direct imaging and simultaneous ion spectroscopy of single clusters with x-ray free-electron lasers such as FLASH in Hamburg allows for analyzing ion spectra of a single cluster of known size irradiated with defined laser intensity [1]. The averaging over focal intensity profile and cluster size distribution - experimental reality in almost all previous studies of lasers with gas-phase targets - typically leads to wash-out of the key signatures. From the x-ray scattering patterns of single clusters the initial state of the cluster can be deduced, its size and shape, as well as the FEL power density the cluster has been exposed to. Our results give strong evidence that the ions from XUV-irradiated large xenon clusters expand only from the surface of a super-dense, almost neutral nanoplasma, while recombination within the fully screened core competes with the expansion process, ultimately bringing it to halt. The dominant recombination strongly shapes the measured ion kinetic energies, resulting in narrow distributions of only fast ions with about a factor of 25 higher ion than electron energies. The size and laser intensity resolved ion spectra allow for detailed studying of the acceleration mechanism and disentangling hydrodynamic and Coulombic contributions. [1] T. Gorkhover et al., PRL 108, 245005 (2012)