In the x-ray region, enough energy is available for making electronic transitions possible.
Figure 1 shows the typical line shape for electronic transitions of individual chromophores in a solid matrix.
The selection rules depend on the symmetry properties of the electronic transition.
The relationship between the energy involved in the electronic transition and the frequency of radiation is given by Planck's law.
In addition to these assignments, electronic transitions also have so-called bands associated with them.
The electronic transition responsible for this absorption is a transition from the 5d to the 6s level.
They can also predict bond strength, the electronic transitions that can take place.
On the other hand, electronic transitions have often yet another 1-2 orders of magnitude larger line strengths.
The electronic transitions of the water molecule lie in the vacuum ultraviolet region.
For some electronic transitions there will also be a Q-branch.