Erlangen 2018 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 6: Atomic Clusters I (joint session A/MO)

MO 6.1a: Vortrag

Montag, 5. März 2018, 16:30–16:45, K 2.016

Imaging the equilibrium shapes of spinning superfluid quantum droplets — •B. Langbehn¹, K. Sander², Y. Ovcharenko^1,3, C. Peltz³, A. Clark⁴, M. Coreno⁵, R. Cucini⁵, P. Finetti⁵, M. Di Fraia⁵, L. Giannessi⁵, C. Grazioli⁵, D. Iablonskyi⁶, A. C. LaForge⁷, T. Nishiyama⁸, V. Oliver Álvarez de Lara⁴, P. Piseri⁹, O. Plekan⁵, K. Ueda⁶, K. C. Prince⁵, F. Stienkemeier⁷, C. Callegari⁵, T. Fennel^3,10, D. Rupp^1,10, and T. Möller¹ — ¹TU Berlin — ²Univ. Rostock — ³European XFEL — ⁴EPFL, Lausanne — ⁵Elettra-Sincrotrone Trieste — ⁶Tohoku Univ. Sendai — ⁷Univ. Freiburg — ⁸Kyoto Univ. — ⁹Univ. di Milano — ¹⁰MBI, Berlin

With the intense short-wavelength femtosecond light pulses from free-electron lasers (FELs) it is now possible to study the structure of unsupported nanoparticles, including superfluid helium nanodroplets. When produced by a free-jet expansion from the liquid phase, these droplets can gain angular momentum. As superfluid droplets cannot rotate in the classical hydrodynamic sense, quantized vortices accommodating the angular momentum are formed inside the droplets. These alter the equilibrium shapes known for normal liquid droplets. In an experiment at the FERMI FEL, we recorded wide-angle scattering images of individual helium nanodroplets. From the diffraction patterns, we reconstructed the full three-dimensional droplet shapes, enabling a comparison to a theoretical model of rotating normal liquid droplets. Surprisingly, the observed shapes of the superfluid droplets match their classical counterparts.