skip to main content

SciTech ConnectSciTech Connect

Title: Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid {sup 4}He

The interaction of a number of impurities (H{sub 2}, Ag, Cu, Ag{sub 2}, Cu{sub 2}, Li, He{sub 3}{sup +}, He{sup *} ({sup 3}S), He{sub 2}{sup ∗} ({sup 3}Σ{sub u}), and e{sup −}) with quantized rectilinear vortex lines in superfluid {sup 4}He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of bothmore » temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He{sup *}.« less
Authors:
;  [1] ;  [2]
  1. Department of Chemistry and Biochemistry, California State University at Northridge, 18111 Nordhoff St., Northridge, California 91330 (United States)
  2. Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States)
Publication Date:
OSTI Identifier:
22416125
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; ATOMS; BINDING ENERGY; COPPER; DENSITY FUNCTIONAL METHOD; ELECTRONS; HELIUM; HELIUM 4; HELIUM IONS; HYDROGEN; IMPURITIES; MOLECULES; POTENTIALS; SILVER; SUPERFLUIDITY; TRAPPING; TRAPS; VORTICES