1
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Affiliation(s)
- Martí Pi
- Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
| | - Francesco Ancilotto
- Dipartimento di Fisica e Astronomia “Galileo Galilei” and CNISM, Università di Padova, via Marzolo 8, 35122 Padova, Italy
- CNR-IOM Democritos, via Bonomea, 265 - 34136 Trieste, Italy
| | - Manuel Barranco
- Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
- Université Toulouse 3, Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
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2
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Abstract
Free superfluid helium droplets constitute a versatile medium for a diverse range of experiments in physics and chemistry that extend from studies of the fundamental laws of superfluid motion to the synthesis of novel nanomaterials. In particular, the emergence of quantum vortices in rotating helium droplets is one of the most dramatic hallmarks of superfluidity and gives detailed access to the wave function describing the quantum liquid. This review provides an introduction to quantum vorticity in helium droplets, followed by a historical account of experiments on vortex visualization in bulk superfluid helium and a more detailed discussion of recent advances in the study of the rotational motion of isolated, nano- to micrometer-scale superfluid helium droplets. Ultrafast X-ray and extreme ultraviolet scattering techniques enabled by X-ray free-electron lasers and high-order harmonic generation in particular have facilitated the in situ detection of droplet shapes and the imaging of vortex structures inside individual, isolated droplets. New applications of helium droplets ranging from studies of quantum phase separations to mechanisms of low-temperature aggregation are discussed.
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Affiliation(s)
- Oliver Gessner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Andrey F. Vilesov
- Department of Chemistry and Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
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3
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Langbehn B, Sander K, Ovcharenko Y, Peltz C, Clark A, Coreno M, Cucini R, Drabbels M, Finetti P, Di Fraia M, Giannessi L, Grazioli C, Iablonskyi D, LaForge AC, Nishiyama T, Oliver Álvarez de Lara V, Piseri P, Plekan O, Ueda K, Zimmermann J, Prince KC, Stienkemeier F, Callegari C, Fennel T, Rupp D, Möller T. Three-Dimensional Shapes of Spinning Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2018; 121:255301. [PMID: 30608832 DOI: 10.1103/physrevlett.121.255301] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/24/2018] [Indexed: 05/12/2023]
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.
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Affiliation(s)
- Bruno Langbehn
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - Katharina Sander
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Yevheniy Ovcharenko
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - Christian Peltz
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Andrew Clark
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Marcello Coreno
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | | | - Marcel Drabbels
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Paola Finetti
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Michele Di Fraia
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Luca Giannessi
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Cesare Grazioli
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | - Denys Iablonskyi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Aaron C LaForge
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - Toshiyuki Nishiyama
- Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | | | - Paolo Piseri
- CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy
| | - Oksana Plekan
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Kiyoshi Ueda
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Julian Zimmermann
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Kevin C Prince
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Victoria 3122, Australia
| | | | - Carlo Callegari
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Thomas Fennel
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Daniela Rupp
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Thomas Möller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
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4
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Baldwin KA, de Fouchier JB, Atkinson PS, Hill RJA, Swift MR, Fairhurst DJ. Magnetic Levitation Stabilized by Streaming Fluid Flows. PHYSICAL REVIEW LETTERS 2018; 121:064502. [PMID: 30141657 DOI: 10.1103/physrevlett.121.064502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/22/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that the ubiquitous laboratory magnetic stirrer provides a simple passive method of magnetic levitation, in which the so-called "flea" levitates indefinitely. We study the onset of levitation and quantify the flea's motion (a combination of vertical oscillation, spinning and "waggling"), finding excellent agreement with a mechanical analytical model. The waggling motion drives recirculating flow, producing a centripetal reaction force that stabilized the flea. Our findings have implications for the locomotion of artificial swimmers and the development of bidirectional microfluidic pumps, and they provide an alternative to sophisticated commercial levitators.
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Affiliation(s)
- K A Baldwin
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - J-B de Fouchier
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - P S Atkinson
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - R J A Hill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - M R Swift
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - D J Fairhurst
- School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
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5
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Liao L, Hill RJA. Shapes and Fissility of Highly Charged and Rapidly Rotating Levitated Liquid Drops. PHYSICAL REVIEW LETTERS 2017; 119:114501. [PMID: 28949221 DOI: 10.1103/physrevlett.119.114501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Indexed: 05/12/2023]
Abstract
We use diamagnetic levitation to investigate the shapes and the stability of free electrically charged and spinning liquid drops of volume ∼1 ml. In addition to binary fission and Taylor cone-jet fission modes observed at low and high charge density, respectively, we also observe an unusual mode which appears to be a hybrid of the two. Measurements of the angular momentum required to fission a charged drop show that nonrotating drops become unstable to fission at the amount of charge predicted by Lord Rayleigh. This result is in contrast to the observations of most previous experiments on fissioning charged drops, which typically exhibit fission well below Rayleigh's limit.
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Affiliation(s)
- L Liao
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - R J A Hill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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6
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Coherent diffractive imaging of single helium nanodroplets with a high harmonic generation source. Nat Commun 2017; 8:493. [PMID: 28887513 PMCID: PMC5591197 DOI: 10.1038/s41467-017-00287-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 06/19/2017] [Indexed: 11/17/2022] Open
Abstract
Coherent diffractive imaging of individual free nanoparticles has opened routes for the in situ analysis of their transient structural, optical, and electronic properties. So far, single-shot single-particle diffraction was assumed to be feasible only at extreme ultraviolet and X-ray free-electron lasers, restricting this research field to large-scale facilities. Here we demonstrate single-shot imaging of isolated helium nanodroplets using extreme ultraviolet pulses from a femtosecond-laser-driven high harmonic source. We obtain bright wide-angle scattering patterns, that allow us to uniquely identify hitherto unresolved prolate shapes of superfluid helium droplets. Our results mark the advent of single-shot gas-phase nanoscopy with lab-based short-wavelength pulses and pave the way to ultrafast coherent diffractive imaging with phase-controlled multicolor fields and attosecond pulses. Diffraction imaging studies of free individual nanoparticles have so far been restricted to XUV and X-ray free - electron laser facilities. Here the authors demonstrate the possibility of using table-top XUV laser sources to image prolate shapes of superfluid helium droplets.
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