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Hi everybody, I've been following this thread and others very intently because I'm becoming very interested in practical amateur spectroscopy.
However there's an aspect which is confusing me, and that's the ionic notation which is often used by some people.
A very long time ago, I studied chemistry - A VERY long time ago, so my memory is not to be relied upon!
But as I recall, 'I' (as in HI, OI, etc) signified the Unionised or Ground state, II signifies the (singly) ionized state, III signifies the doubly ionized state, IV the triply ionized state, and so on.
The '[]' (as in [OIII]) indicated a forbidden transition, commonly seen in low density gaseous nebulae, etc.
Yet I've seen, say, the 'II' notation (whether forbidden or not) referred to here and elsewhere as double ionization, rather than single, and 'III' as triple ionization.
Am I missing something, or is the latter use of the notation erroneous?
Thanks guys.
Zaps.
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