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Title: Site-specific vibrational spectral signatures of water molecules in the magic H 3O +(H 2O) 20 and Cs +(H 2O) 20 clusters

Here, theoretical models of proton hydration with tens of water molecules indicate that the excess proton is embedded on the surface of clathrate-like cage structures with one or two water molecules in the interior. The evidence for these structures has been indirect, however, because the experimental spectra in the critical H-bonding region of the OH stretching vibrations have been too diffuse to provide band patterns that distinguish between candidate structures predicted theoretically. Here we exploit the slow cooling afforded by cryogenic ion trapping, along with isotopic substitution, to quench water clusters attached to the H 3O + and Cs + ions into structures that yield well-resolved vibrational bands over the entire 215- to 3,800-cm -1 range. The magic H 3O +(H 2O) 20 cluster yields particularly clear spectral signatures that can, with the aid of ab initio predictions, be traced to specific classes of network sites in the predicted pentagonal dodecahedron H-bonded cage with the hydronium ion residing on the surface.
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ;  [5] ;  [4]
  1. Yale Univ., New Haven, CT (United States)
  2. Yale Univ., New Haven, CT (United States); Stony Brook Univ., Stony Brook, NY (United States)
  3. Fritz-Haber-Institut de Max-Planck-Gesellschaft, Berlin (Germany)
  4. Univ. Leipzig, Leipzig (Germany)
  5. Fritz-Haber-Institut de Max-Planck-Gesellschaft, Berlin (Germany); Univ. Leipzig, Leipzig (Germany)
Publication Date:
Grant/Contract Number:
FG02-06ER15800; CHE-1213634; FA9550-13-1-0007; CNS 08-21132
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 111; Journal Issue: 51; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Yale Univ., New Haven, CT (United States)
Sponsoring Org:
USDOE; National Science Foundation (NSF); US Air Force; US Department of Defense (DOD)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; cryogenic vibrational spectroscopy; hydrogen bonding; water clusters
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1348391