I was taking a look at Jablonski schemes and had some doubts regarding it. Now assume a regular molecule which follows this Jablonski scheme:
We can see that when molecules absorb certain quantized wavelengths, they get promoted to vibrationally excited, excited electronic states. But when they emit the photon again, they do that from the vibrationally lowest, lowest excited electronic state (vibrational ground state of S1 (or T1 for phosphorescence)), this is a result from Kasha's rule.
However, when they emit photons, does it happen to any of the vibrationally excited states of the electronic ground state (although the probability into which vibrational mode of S0 is given by the Franck-Condon-principle) or into a specific one? Is there such a rule?
Edit: As I am currently working on lanthanides, investigating the antenna effect. I was wondering which states the excited electronic atomic states (see the diagram) decay to; the picture shows all kinds of terms can be emitted to, but I am not sure in what proportion. Also, one usually only detects one emitted wavelength in these kinds of complexes (especially of Eu3+, since I worked with it), but I don't understand why because there should be many emission lines: