A significant fraction of superfluid helium nanodroplets produced in a free-jet expansion has been observed to gain high angular momentum resulting in large centrifugal deformation. We measured single-shot diffraction patterns of individual rotating helium nanodroplets up to large scattering angles using intense extreme ultraviolet light pulses from the FERMI free-electron laser. Distinct asymmetric features in the wide-angle diffraction patterns enable the unique and systematic identification of the three-dimensional droplet shapes. The analysis of a large data set allows us to follow the evolution from axisymmetric oblate to triaxial prolate and two-lobed droplets. We find that the shapes of spinning superfluid helium droplets exhibit the same stages as classical rotating droplets while the previously reported metastable, oblate shapes of quantum droplets are not observed. Our three-dimensional analysis represents a valuable landmark for clarifying the interrelation between morphology and superfluidity on the nanometer scale.

Three-Dimensional Shapes of Spinning Helium Nanodroplets / B. Langbehn, K. Sander, Y. Ovcharenko, C. Peltz, A. Clark, M. Coreno, R. Cucini, M. Drabbels, P. Finetti, M. Di Fraia, L. Giannessi, C. Grazioli, D. Iablonskyi, A.C. Laforge, T. Nishiyama, V. Oliver Álvarez De Lara, P. Piseri, O. Plekan, K. Ueda, J. Zimmermann, K.C. Prince, F. Stienkemeier, C. Callegari, T. Fennel, D. Rupp, T. Möller. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 121:25(2018), pp. 255301.1-255301.6.

Three-Dimensional Shapes of Spinning Helium Nanodroplets

P. Piseri;
2018

Abstract

A significant fraction of superfluid helium nanodroplets produced in a free-jet expansion has been observed to gain high angular momentum resulting in large centrifugal deformation. We measured single-shot diffraction patterns of individual rotating helium nanodroplets up to large scattering angles using intense extreme ultraviolet light pulses from the FERMI free-electron laser. Distinct asymmetric features in the wide-angle diffraction patterns enable the unique and systematic identification of the three-dimensional droplet shapes. The analysis of a large data set allows us to follow the evolution from axisymmetric oblate to triaxial prolate and two-lobed droplets. We find that the shapes of spinning superfluid helium droplets exhibit the same stages as classical rotating droplets while the previously reported metastable, oblate shapes of quantum droplets are not observed. Our three-dimensional analysis represents a valuable landmark for clarifying the interrelation between morphology and superfluidity on the nanometer scale.
Free-electron laser; stability; configurations; droplets; coherent; spectra; drops
Settore FIS/03 - Fisica della Materia
NOXSS (X-ray Single Shots of Nano Objects) un approccio sperimentale e teorico integrato per la caratterizzazione strutturale di nano e micro oggetti (clusters, nanocristalli, biomolecole, virus, liposomi) utilizzando gli impulsi X ultrabrevi ed ultrabrillanti delle sorgenti free electron laser europee
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/634774
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