He II, O III lines?

  1. Hi everyone,

    I think this is a relatively straightforward question, but I can't find a simple answer for it on Google.
    What do the Roman numerals stand for in He II and O III in relation to spectroscopy?

  2. jcsd
  3. Ken G

    Ken G 3,603
    Gold Member

    He I is neutral, He II is once ionized, etc. A clunky notation, to be sure-- kind of like how 2011 is the "21st century."
  4. Thanks, that rings a bell alright - had a feeling it was something along those lines (no pun intended...) Cheers :D
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