For special glasses, crystals, or gases absorb energy from an electrical current or another laser they become "excited." The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom's nucleus. When they return to their normal or "ground" state, the electrons emit photons.
I think the excited electron is always the valence electron. However In metals the valence electrons are not contained to orbitals, they exist in a sea of electrons that flow freely through the object. Does this mean that valence electrons in metals can not be excited or can not move up orbitals? or perhaps the next electron in line moves up an orbital. If so does it join the sea of electrons? (I'm just throwing out ideas here).
Maybe I'm misunderstanding what it means to be 'excited' because, as it says, energy from current can excite electrons.
Any insight is appreciated.