For example , one can say for a given transition that it corresponds to the excitation of an electron from an occupied orbital to a given unoccupied orbital .
The atomic orbital concept is therefore a key concept for visualizing the excitation process associated with a given transition .
One can say for a given transition that it corresponds to the excitation of an electron from an occupied orbital to a given unoccupied orbital .
The atomic orbital concept is therefore a key concept for visualizing the excitation process associated with a given transition .