Düsseldorf 2007 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 22: Poster II - Atomic clusters

A 22.11: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster B

Coherent Diffractive Imaging of Atomic Clusters with XFEL Pulses — •Christian Gnodtke, Ulf Saalmann, and Jan-Michael Rost — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden, Germany

We study the possibility of coherent diffractive imaging of atomic clusters with intense, femtosecond pulses from X-ray free electron lasers (XFEL). We simulate the diffraction patterns of rare-gas clusters with radii ranging from a few to tens of nanometers in X-ray pulses with laser wavelengths of 32nm, as currently available at FLASH, down to 1Å  as will be available from the XFEL at DESY in Hamburg in the future. At large wavelengths intrinsic or induced density inhomogeneities within the cluster on a length-scale comparable to the laser wavelength may become visible in an imaging experiment. Towards shorter wavelengths we approach atomic resolution, which, at a wavelength of 1Å, is limited only by the radiation damage inflicted on the sample by the pulse. We calculate the damage threshold by detailed microscopic simulation of the laser-induced dynamics using quantum-mechanical transition rates combined with a molecular dynamics simulation of the (quasi-)free electrons and ions. Finally, we make use of iterative oversampling algorithms to invert the simulated diffraction patterns to real-space images of the cluster.