Photon excitation to full orbitals

[ngc2024]

In introductory physics and chemistry, photon excitation is usually illstrated with a simple hydrogen molecule. I am wondering what happens if an electron is excited to an orbital that is already full. Would the orbital split up into different energy levels as hybridisation, so as not to violate the pauli exlusion principle?

 

[DrClaude]

You can't excite an electron to a filled orbital.

 

[ngc2024]

So that means that a photon with energy corresponding to the energy difference between, say n=1 and n=2, would not be absorbed if n=3 is filled?

 

[DrClaude]

So that means that a photon with energy corresponding to the energy difference between, say n=1 and n=2, would not be absorbed if n=3 is filled?

These numbers are not quite correct. But say that you have F^- in the electronic configuration 1s²2s²2p⁶: even if you have photons of energy E_2p-E_1s, there will be no absorption, while you would have absorption for neutral fluorine.

 

[Chandra Prayaga]

The phenomenon is called Spectral Hole Burning. If the upper absorption level is not full, the material will absorb the light. But you can selectively fill upper levels and make the material transparent to that particular frequency. Here is a reference:
https://en.wikipedia.org/wiki/Spectral_hole_burning

 

[DrClaude]

The phenomenon is called Spectral Hole Burning.

Just to be clear: while spectral hole burning is a manifestation of what we are discussing, it applies only to cases where there is initially absorption. In the example I mentioned, the orbitals were already filled.

 

[ngc2024]

Thank you both - that is very interesting!

 

[UncertaintyAjay]

It has to do with Pauli's exclusion principle. No two electrons can occupy the same quantum state. So you cannot excite an electron to a filled orbital.
Note: Pauli's exclusion principle does not apply only to electrons but to an entire class of particles- fermions.

 

[Chandra Prayaga]

Just to be clear: while spectral hole burning is a manifestation of what we are discussing, it applies only to cases where there is initially absorption. In the example I mentioned, the orbitals were already filled.

Yes. All that has happened in your case is that you are half way through the process.

 

[JoeyCentral]

Not to be offtopic, but isn't this more of a general chemistry related question? This is exactly what I learned in my chemistry class.