Re: Energy level diagrams

[John Denker <jsd@AV8N.COM>]

Pete Lohstreter wrote:
>> who set up the lettering scheme.
> I think the question is about lettering the
> principle orbit locations not the orbitals.  For instance, the first orbit
> is either designated as '1' or 'K'  the second is '2' or 'L'  etc...

Two answers, one phenomenological, one theoretical;

The lettering goes back to the earliest days of Xray
spectroscopy.  Barkla labelled the various series of
lines observed in the spectrum.
  http://www.nobel.se/physics/laureates/1917/barkla-lecture.pdf

Kossel's interpretation of the various series in terms
of atomic energy levels came somewhat later.
  http://www-ssrl.slac.stanford.edu/mes/hlights.html#briefhistory