Berlin 2014 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 30: Interaction with VUV and X-ray light I

A 30.2: Vortrag

Mittwoch, 19. März 2014, 14:30–14:45, BEBEL E42

Time-resolved x-ray imaging of laser-driven hydrogen nanoclusters: a microscopic particle-in-cell analysis — •Christian Peltz¹, Charles Varin², Thomas Brabec², and Thomas Fennel¹ — ¹Institute of Physics, University of Rostock, Germany — ²Department of Physics and Centre for Photonics Research,University of Ottawa, Canada

We investigate the time-dependent evolution of laser-heated R = 25 nm solid-density hydrogen clusters via coherent diffractive imaging for an infrared pump/x-ray probe scenario. Our microscopic particle-in-cell analysis provides a full electromagnetic description of both the droplet ionization and expansion induced by the intense few-cycle pump pulse as well as the coherent light scattering by the x-ray probe in the expanding nano-plasma [1]. Unexpectedly, the time-resolved scattering images show Mie-like diffraction pattern with increasing fringe separations as function of delay that indicate a shrinking of the cluster. Our analysis reveals that this effect results from continuous ion ablation on the cluster surface which generates a simple self-similar radial density profile whose evolution can be reconstructed precisely by fitting the time-resolved scattering images using a simplified scattering model in Born approximation. Our findings suggest, that time-resolved diffractive imaging experiments on nano-droplets will provide unprecedented insights into the physics of ion expansion and surface ablation in laser-driven plasmas.

[1] C. Varin, C. Peltz, T. Brabec and T. Fennel , Phys. Rev. Lett. 108, 175007 (2012)