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Extracting the magic numbers of water clusters from abundance spectra

This study explores the phenomenon of "magic" water clusters with N=21 through electrospray source and TOF-MS ion production. It investigates the cooling time and ion product determination, as well as evaporative ensemble abundances and activation energies. Two examples are provided for further understanding. The study also touches on thermal properties and radiative heating.

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Extracting the magic numbers of water clusters from abundance spectra

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  1. Extracting the magic numbers of water clusters from abundance spectra K.Hansen, Dept. of Physics, Göteborg University P.Andersson, Dept. of Chemistry, Atmospheric Science, Göteborg University E.Uggerud, Dept. of Chemistry, Universitetet i Oslo

  2. Pure water clusters H+(H2O)n N=21 (it is ”magic”)

  3. Electrospray source & TOF-MS Ion production (Quadrupole mass filter, off) (collision cell, empty) Transit time defines cooling time Ion product determination (TOF-MS)

  4. Evaporative ensemble abundances: abundances / smoothened abundance distribution evaporative activation energies smoothened ditto heat capacity/kB evaporative rate constant frequency factor

  5. Example 1: Na cluster separation energies compared with heat bath evaporation J.Borggreen et al., Phys.Rev. A 62 (2000) 013202.

  6. Example 2: Gold clusters in Penning trap compared with modelfree data L. Schweikhard et al. Eur.Phys.J.D 36 (2005) 179

  7. Conclusions: ’Magic’ appearance of N=21 is due both to enhanced stability of 21 and reduced stability of 22. N=28, 55 appear magic because 29, 56 are anti-magic Need to understand better: Thermal properties Radiative heating

  8. Metastable fragmentation Z.Shi et al., JCP 99 (1993) 8009

  9. Radiative heating Th.Schindler et al., CPL 250 (1996) 301

  10. Z.Shi et al., JCP 99 (1993) 8009

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