Erlangen 2018 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 9: Atomic Clusters II (joint session A/MO)

MO 9.4: Vortrag

Dienstag, 6. März 2018, 14:45–15:00, K 2.016

Coherent diffraction images of isolated helium nanodroplets obtained with a high harmonic source — N. Monserud¹, B. Langbehn², P. Nuñez von Voigt², M. Sauppe², A. Spanier², J. Zimmermann^1,2, Y. Ovcharenko^2,3, T. Möller², F. Frassetto⁴, L. Poletto⁴, A. Trabattoni⁵, F. Calegari^5,6, M. Nisoli^6,7, K. Sander⁸, C. Peltz⁸, T. Fennel^1,8, B. Schütte¹, M.J.J. Vrakking¹, A. Rouzée¹, and •D. Rupp^1,2 — ¹Max-Born-Institut Berlin — ²TU Berlin — ³European XFEL — ⁴CNR Padova — ⁵CFEL@DESY — ⁶CNR Milano — ⁷Politecnico di Milano — ⁸Universität Rostock

We recently demonstrated single-shot coherent diffractive imaging of individual gas-phase nanoparticles with a table-top light source (Nat. Comm. 8, 493 (2017)). In the present work, superfluid helium nanodroplets were irradiated by intense extreme ultraviolet (XUV) pulses from high-order harmonic generation (HHG). The single-shot XUV spectra of the multicolor pulses were measured in coincidence. From the diffraction images, a majority of spherical droplets and a small fraction of rotationally distorted prolate shapes could be identified. Further, the spherical diffraction images were analyzed via multicolor Mie fits and the refractive indices at the harmonic wavelengths were extracted. They are a sensitive measure of changes in the electronic structure and thus can serve as a handle for tracking ultrafast excitation and ionization dynamics in the droplets in time-resolved imaging approaches - ultimately with intense attosecond pulses, that are currently under development at HHG sources and free-electron lasers.