Fingerprints of microscopic superfluidity in HHen+ clusters

Attila G. Császár, Tamás Szidarovszky, Oskar Asvany, Stephan Schlemmer

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5 Citations (Scopus)


The structures and the vibrational dynamics of the complexes HHe + n are investigated experimentally (via mass spectrometry (MS)) and at high levels of electronic-structure theory. The MS measurements reveal interesting trends about the stability of the starting members of the HHe + n family. The computations establish that the basically linear, strongly bound, symmetric triatomic molecular ion He(H + )He, with an equilibrium H–He distance of 0.925 Å and about 2/3 but at least 1/2 of the positive charge on H, is the molecular core of all of the n ≥ 3 complexes. Definitive quantum-chemical results are obtained for HHe + and HHe + 2 , including the proton affinity of He (computed to be 14, 876 ± 12 cm −1  via the focal-point analysis (FPA) scheme), the FPA isomerisation energy between the two linear isomers of HHe + 2 (3826 ± 20 cm −1 ), and the dissociation energy of the HHe + 2 ****HHe + + He reaction, with an FPA estimate of 3931 ± 20 cm −1 . The structural isomers of the He-solvated complexes are discussed up to n=18. A useful notation, [k−l−m]-HHe + n , is introduced to characterise qualitatively the three possible belts around the He–H + –He core in HHe + n (n ≥ 3), where l denotes the number of He atoms in the central belt and k ≥ m denote the number of He atoms in the top and bottom belts. Capping He atoms attached to the belts can be indicated by sub- and superscripts. Several possible indicators of microscopic superfluidity are investigated: He evaporation energies, rotational constants, and vibrational fundamentals.

Original languageEnglish
Pages (from-to)1559-1583
Number of pages25
JournalMolecular Physics
Issue number9-12
Publication statusPublished - Jun 18 2019


  • HHe
  • HHe
  • He-solvated proton
  • Microscopic superfluidity
  • electronic-structure computations
  • mass spectrum

ASJC Scopus subject areas

  • Biophysics
  • Molecular Biology
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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