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Re: Energy level diagrams

According to Herzberg, Atomic Spectra and Atomic Structure, 1945, the principal series contains energy transitions that start on the 1S level and end on any of the P levels above.

The sharp series starts on the 2P level and ends on an S level.

The diffuse series starts on the 2P and ends on a D level.

The series that starts on the 3D level and ends on an F level is called the Bergmann series. Why this is called "fundamental" now is not clear in his book.

Since the principal series deals with transitions from the ground energy state, the name makes sense. It also makes sense that these spectral lines would be bright (both in absorption and emission). We also know, due to selection rules, that the transitions must go to (or come from) a P state.

Beyond this, I think a spectroscopist might be able to give more insight but I am not sure there is too much more fundamental meaning that can be ascribed to the S, P, D, and F designation (than has already been discussed in this thread). The history, of course, is fascinating. I will enjoy a discussion in a decade or so about where terms like "color," "strange," and "charm" came from.

Cheers,

Rick

Richard E. Swanson, Ph.D.
Dean of Instruction
Physics Professor
Sandhills Community College, Pinehurst, NC 28374
swansonr@sandhills.edu (910) 695-3715

anngeorg@PACBELL.NET 06/06/04 04:46PM >>>
More than it -- I just needed the meaning of principle, i.e. higher
intensity (brighter), except I don't understand how fundamental means
isolated.

Is it simply selection rules that make p lines brighter (not violated)?

bc, endangered by a little knowledge

Brian Whatcott wrote:

At 07:36 PM 6/5/2004, BC, you wrote:


I'm still waiting for p and f. I Googled for about 10' and then gave
up. Anyone else know?

bc



s,p,d,f stand for sharp, principal, diffuse, fundamental.
The names (and abbreviations) come from the earliest work
in spectroscopy -- any effort to sort out the various
spectral lines, long before there was any understanding
of atomic structure.

http://www.google.com/search?q=3Dsharp+principal+diffuse=20
http://w3.msi.vxu.se/~pku/Rydberg/LifeWork.html




Hmmm, in your note you quote the explanation (above)
that p stands for principal and f for fundamental, from the appearance
of the spectral lines in the spectroscope. So I have to suppose that
your continued puzzlement might be resolved if someone were
able to answer a question in this form:

"What atomic mechanisms determine the relative intensities of certain
lines which are bright enough to be called 'principal"?

And what features are said to be responsible for the absence of
emissions at nearby frequencies to that of a line feature in the
spectrometer which attracts the descriptor "fundamental". "

Is that it?



Brian Whatcott Altus OK Eureka!