Sketching Energy Diagram w/ l=2, s=1/2 - m, j & mj values

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Homework Help Overview

The original poster attempts to sketch an energy diagram for a quantum system characterized by angular momentum quantum number l = 2 and spin quantum number s = 1/2. The discussion revolves around the effects of spin-orbit coupling and an external magnetic field on the energy levels, including the labeling of magnetic quantum numbers (m values) and total angular momentum (j values).

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the initial confusion regarding the inclusion of m values before spin-orbit splitting and the impact of an external magnetic field on energy levels. Questions arise about the relative effects of spin-orbit coupling versus the external magnetic field, as well as the necessity of drawing additional energy levels for different states.

Discussion Status

Some participants have provided guidance on the relevance of the Zeeman effect and the need for clarity in the energy-level diagram. There is an ongoing exploration of how to represent the energy levels accurately, with varying interpretations of what should be included in the diagram.

Contextual Notes

Participants are navigating the constraints of their homework requirements, including the specific energy levels to be examined and the definitions of quantum numbers involved. There is mention of confusion regarding the Zeeman effect and its representation in the context of the problem.

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Homework Statement


Sketch the energy diagram for a system with l = 2 and s = 1/2: before spin-orbit splitting, after spin-orbit splitting, after additional application of external magnetic B (label all m values).


Homework Equations


m values from -l to l (total 2l+1 values)
j values from l-s to l+s
mj values from -j to j (total 2j+1 values)


The Attempt at a Solution


I drew a diagram but I'm not sure if it's right. and before the spin-orbit splitting I was confused, so I just drew the m values for l (not sure though).

En_Diagram.png
 
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If the electron magnetic moment did not interact with the nuclear magnetic moment, would there be any difference between the energy level of different orientations of the spin?

An additional magnetic field produces the Zeeman effect.
That is something you can look up.

Which has the bigger effect: the spin-orbit coupling or the external magnetic field?
 
I don't think there would be any change in the energy level without B field. so I don't think I need to include the m values for l=2 without spin.. I have an example of the Zeeman effect but i don't really understand it. it shows arrows going down from the lines, do I need to draw a l=1 diagram if the energies go from D (l=2) to P state? I think the external B field would have a greater effect because it has more energy levels, the spin-orbit only has like 5 levels.
 
Last edited:
Technically the Zeeman effect is the fine splitting, in the presence of a magnetic field, of the spectral lines you get when there is no magnetic field. The arrows in your notes show the transitions that give rise to the spectra.

You only need the energy-level diagram.
You should only draw as many energy levels as you have been asked to examine.

You can find articles about zeeman effect and spin-orbit coupling online.
I gave you the names as a way of hinting you should look them up ;)
 
I made another drawing, don't have the arrows because I don't think I need it, would it be something like this? there are 5 levels now before the B field. I tried looking up zeeman effect but i was confused because it looked different from my problem.

En_Diagram2.png
 
Last edited:
You have decided that the spin-orbit splitting is bigger than the effect of the magnet?
You have decided that "a system with l=2" means to include l=0 and l=1 as well?
If so then you have got what you wanted.

These are decisions for you to make though, because it is your course.
 

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