Detection of long-living neutral hydrated clusters in laboratory simulation of ionospheric D region plasma

H. S.S. Sinha, Koh Ichiro Oyama, S. Watanabe

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1 Citation (Scopus)


The existence of hydrated cluster ions is known through in situ measurements in the D region of the ionosphere and laboratory simulation experiments. A series of experiments were conducted at Sagamihara, Japan with the intention of detecting some of the ions which, although predicted, had eluded detection in laboratory simulation. The other motivation was to look for heavier ions in laboratory simulations in conditions close to those in the D region. With the availability of better ion mass spectrometers, these could supposedly be detected by rocket measurements. Results of these experiments point to a new aspect, namely, the production of a neutral hydrated cluster molecule, which (a) has ionization potential of less than 10.2 eV, (b) has lifetimes in excess of 90 min, and (c) is formed within a limited pressure range. As this neutral cluster molecule has a mass number of 102, most probably it is NO×(H2O)4. A number of other important ions, which were detected earlier in laboratory experiments, were also seen in our data. These include NO+(H2O)n, NO +(H2O)nX, NO2+(H 2O)n, H3O+(H2O) n, H3O+(H2O)nX, and O2+(H2O)n series. A few clusters {36+(H3O+OH), 60+(NO+NO) and 63+(NO+HO2)} and molecular ions {29 +(N2H+), 33+(HO2 +) and 43+(N3H+)} were also detected in these experiments. It was also found that, like the earlier experiments, the concentration of most of the hydrated ions showed an oscillatory behavior. The ion formation was observed only within a limited pressure range, which corresponds to the 50 to 100 km altitude range of the ionosphere.

Original languageEnglish
Pages (from-to)583-589
Number of pages7
JournalJournal of Geophysical Research: Space Physics
Issue number1
Publication statusPublished - 2013

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Geophysics


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