Feinberg, Alexandra J.Verma, DeepakO'Connell-Lopez, Sean M. O.Erukala, SwethaTanyag, Rico Mayro P.Pang, WeiwuSaladrigas, Catherine A.Toulson, Benjamin W.Borgwardt, MarioShivaram, NiranjanLin, Ming-FuAl Haddad, AndreJager, WolfgangBostedt, ChristophWalter, PeterGessner, OliverVilesov, Andrey F.2022-03-282022-03-282022-03-282021-12-0110.1126/sciadv.abk2247https://infoscience.epfl.ch/handle/20.500.14299/186755WOS:000768285000002Quantum fluid droplets made of helium-3 (He-3) or helium-4 (He-4) isotopes have long been considered as ideal cryogenic nanolabs, enabling unique ultracold chemistry and spectroscopy applications. The droplets were believed to provide a homogeneous environment in which dopant atoms and molecules could move and react almost as in free space but at temperatures close to absolute zero. Here, we report ultrafast x-ray diffraction experiments on xenon-doped He-3 and He-4 nanodroplets, demonstrating that the unavoidable rotational excitation of isolated droplets leads to highly anisotropic and inhomogeneous interactions between the host matrix and enclosed dopants. Superfluid He-4 droplets are laced with quantum vortices that trap the embedded particles, leading to the formation of filament-shaped clusters. In comparison, dopants in He-3 droplets gather in diffuse, ring-shaped structures along the equator. The shapes of droplets carrying filaments or rings are direct evidence that rotational excitation is the root cause for the inhomogeneous dopant distributions.Multidisciplinary SciencesScience & Technology - Other Topicssuperfluid-heliumliquidvisualizationspectroscopymoleculesimpurityclusterstext::journal::journal article::research article