Heidelberg 2015 – scientific programme

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MO: Fachverband Molekülphysik

MO 6: Atomic clusters (with MO)

MO 6.5: Poster

Monday, March 23, 2015, 17:00–19:00, C/Foyer

Microscopic description of single-shot diffractive imaging of atomic clusters — •Katharina Sander, Christian Peltz, and Thomas Fennel — Institute of Physics, University of Rostock

The availability of intense femtosecond laser pulses in the XUV and soft x-ray spectral range from free-electron lasers has made it possible to investigate the structure and dynamics of nanosystems via single-shot diffractive imaging experiments, as recently demonstrated with single clusters [1]. To study the linear light scattering in clusters theoretically we employ the discrete dipole approximation (DDA) [2]. The DDA method relies on a dyadic Greens function approach and allows to model arbitrarily shaped targets down to the atomic level. We propose a modified complex mixing scheme to increase convergence of the iterative DDA model. As a first application, we examine the possibility of imaging the recently predicted IR induced nonlinear internal plasma waves in clusters [3]. Our analysis supports that distinct features of the sub-fs dynamics can be extracted from time-resolved scattering pictures. Second, we investigate the scattering of strongly absorbing silver clusters. A comparison with experimental results highlights the necessity to include absorption, which is neglected in the regularly applied treatment of x-ray scattering (Born approximation). Finally, we analyze the limits for the applicability of the single-frequency approximation in the modelling of scattering images.

[1] T. Gorkhover et al., Phys. Rev. Lett. 108, 245005, (2012)

[2] E. M. Purcell et al., Astrophys. J. 186, 705-714, (1973)

[3] C. Varin et al., Phys. Rev. Lett. 108, 175007, (2012)