Question regarding spectroscopic notation

In summary, there are two different conventions for characterizing atomic states: one using spin quantum numbers, orbital letters, and energy levels, and another using total spin, orbital angular momentum, and total angular momentum. When interpreting a paper discussing atomic transitions, it is important to remember the rules for angular momentum addition in quantum mechanics. The notation ##^5S_2\rightarrow \left.^3P_{2,1}\right.## indicates that the angular momentum on the left side is 2 and the angular momentum on the right side is either 2 or 1, depending on the specific transition.
  • #1
Telemachus
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I think there are different conventions. Once I worked with XPS, and there we used the spin quantum number, the letter for the orbital, and a number for the energy leverl I think, to characterize photoelectrons.

Another notation uses, to characterize an atomic state, the convention ##^{2S+1}L_J##, where S is the total spin, L is the orbital angular momentum (characterized with a capital letter, S,P,D,F, etc), and J is the total angular momentum.

However, now I was trying to interpret this paper: http://adsabs.harvard.edu/full/1983ApJ...275L..19M

There are some atomic transitions involved, where relaxation of an atom delivers a photon, for example, in the abstract it is mentioned ##^5S_2\rightarrow \left.^3P_{2,1}\right.##. I'm not sure on how to interpret this, because if it where ##2S+1=5##, on the right hand side I would have ##S=2##, and as is an S orbital, the orbital angular momentum should be 0, which would give ##J=2##, but it should be ##J=3##. How should I interpret this?EDIT: I think I have realized what is going on. I have forgotten after a while about angular momentum addition in quantum mechanics, I think the issue has to do with that.
 
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  • #2
So, for the example in the abstract, you have ##^5S_2\rightarrow \left.^3P_{2,1}\right.##. What this means is that the angular momentum of the state on the left hand side is 2, and the angular momentum of the right hand side is either 2 or 1, depending on the transition. So, for the right hand side you have a P orbital, which has an angular momentum of 1, and then you add the total angular momentum (which is 2) to get either 3 or 2, depending on the transition. Is this correct?
 

1. What is spectroscopic notation?

Spectroscopic notation is a shorthand way of representing the electronic configuration of an atom or ion. It uses a combination of letters and numbers to indicate the energy level, sublevel, and number of electrons in each sublevel.

2. How is spectroscopic notation written?

Spectroscopic notation is written with the energy level number followed by a letter representing the sublevel (s, p, d, f) and a superscript number indicating the number of electrons in that sublevel. For example, the notation for the first energy level with one electron in the s sublevel would be written as 1s1.

3. Why is spectroscopic notation important?

Spectroscopic notation is important because it allows scientists to easily represent and compare the electronic configurations of different atoms and ions. It also provides information about the energy levels and sublevels that are occupied by electrons, which is crucial for understanding the chemical properties of an element.

4. How is spectroscopic notation different from electron configuration?

Spectroscopic notation and electron configuration are both ways of representing the arrangement of electrons in an atom or ion. The main difference is that spectroscopic notation uses a combination of letters and numbers, while electron configuration uses a combination of numbers, letters, and arrows to indicate the energy levels, sublevels, and spin of each electron.

5. Can spectroscopic notation be used for all elements?

Yes, spectroscopic notation can be used for all elements. However, it is most commonly used for elements with relatively simple electronic configurations. For more complex elements, a different notation system called orbital notation may be used.

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