Photoexcitation stages of an atom?

[HMS-776]

Just wondering about photoexcitation of an atom.

Say I have an atom that has excitation wavelengths of 500nm, 450nm, and 300nm.

If I want to get to the level that is equal to 300nm, do I have to first hit the atom with the 500nm, and 450nm. Or can I just hit the atom with 300nm?

Does excitation have to be done in stages or can one just use a single photon to excite the atom to a specific level?

[Bob S]

Just wondering about photoexcitation of an atom. Say I have an atom that has excitation wavelengths of 500nm, 450nm, and 300nm. If I want to get to the level that is equal to 300nm, do I have to first hit the atom with the 500nm, and 450nm. Or can I just hit the atom with 300nm? Does excitation have to be done in stages or can one just use a single photon to excite the atom to a specific level?
Hello HMS again-
You cannot get to the 2S or 3D etc. from the 1S. You can get to the 2P or 3P etc. from the 1S. You can get to the final state with one photon if delta L = 1.
Review the physics of electronic transitions in atoms..
Bob S

[HMS-776]

I guess I need to be more specific, I'm wondering about the following:


http://i642.photobucket.com/albums/uu141/Hms-776/OxygenElectronicstatesdiagram-1.gif

Say I have all the wavelengths below from 1269-381 nm. What wavelengths would I need to excite the liquid oxygen to it's highest possible energy?

What wavelengths would not be needed?